diff --git a/api/src/services/hierarchy/lineage-manipulation.js b/api/src/services/hierarchy/lineage-manipulation.js
new file mode 100644
index 00000000000..542ff0e62e2
--- /dev/null
+++ b/api/src/services/hierarchy/lineage-manipulation.js
@@ -0,0 +1,40 @@
+/**
+ * Lineage manipulation helpers for hierarchy operations (move/merge).
+ *
+ * Ported from cht-conf `src/lib/hierarchy-operations/lineage-manipulation.js`, minus its
+ * `minifyLineagesInDoc`: that function duplicates `@medic/lineage`'s `minify`, which is available
+ * server-side, so callers should use `require('@medic/lineage')(Promise, db).minify` instead of
+ * porting a copy. The remaining helpers (`createLineageFromDoc`, `pluckIdsFromLineage`) and the
+ * re-exported `replace-lineage` functions have no shared-lib equivalent and are ported here.
+ */
+
+const { replaceContactLineage, replaceParentLineage } = require('./replace-lineage');
+
+const createLineageFromDoc = doc => {
+  if (!doc) {
+    return undefined;
+  }
+
+  return {
+    _id: doc._id,
+    parent: doc.parent || undefined,
+  };
+};
+
+/*
+Given a lineage, return the ids therein
+*/
+const pluckIdsFromLineage = (lineage, results = []) => {
+  if (!lineage) {
+    return results;
+  }
+
+  return pluckIdsFromLineage(lineage.parent, [...results, lineage._id]);
+};
+
+module.exports = {
+  createLineageFromDoc,
+  pluckIdsFromLineage,
+  replaceParentLineage,
+  replaceContactLineage,
+};
diff --git a/api/src/services/hierarchy/replace-lineage.js b/api/src/services/hierarchy/replace-lineage.js
new file mode 100644
index 00000000000..0edda83441f
--- /dev/null
+++ b/api/src/services/hierarchy/replace-lineage.js
@@ -0,0 +1,86 @@
+/**
+ * Lineage replacement helpers for hierarchy operations (move/merge).
+ *
+ * Ported from cht-conf `src/lib/hierarchy-operations/replace-lineage.js`. These are pure functions
+ * (no I/O) that rewrite the embedded `parent`/`contact` lineage of a document in place. They are
+ * shared by the move and merge services; the `params.merge` flag selects the merge variant.
+ */
+
+const replaceEntireLineage = (replaceInDoc, lineageAttributeName, replaceWith) => {
+  if (!replaceWith) {
+    const lineageWasDeleted = !!replaceInDoc[lineageAttributeName];
+    replaceInDoc[lineageAttributeName] = undefined;
+    return lineageWasDeleted;
+  }
+
+  replaceInDoc[lineageAttributeName] = replaceWith;
+  return true;
+};
+
+const replaceLineageForMove = (doc, lineageAttributeName, params) => {
+  let currentElement = doc[lineageAttributeName];
+  while (currentElement) {
+    if (currentElement?._id === params.startingFromId) {
+      return replaceEntireLineage(currentElement, 'parent', params.replaceWith);
+    }
+
+    currentElement = currentElement.parent;
+  }
+
+  return false;
+};
+
+const replaceLineageForMerge = (doc, lineageAttributeName, params) => {
+  let currentElement = doc;
+  let currentAttributeName = lineageAttributeName;
+  while (currentElement) {
+    if (currentElement[currentAttributeName]?._id === params.startingFromId) {
+      return replaceEntireLineage(currentElement, currentAttributeName, params.replaceWith);
+    }
+
+    currentElement = currentElement[currentAttributeName];
+    currentAttributeName = 'parent';
+  }
+
+  return false;
+};
+
+const replaceLineage = (doc, lineageAttributeName, params) => {
+  // Replace the full lineage
+  if (!params.startingFromId) {
+    return replaceEntireLineage(doc, lineageAttributeName, params.replaceWith);
+  }
+
+  const selectedFunction = params.merge ? replaceLineageForMerge : replaceLineageForMove;
+  return selectedFunction(doc, lineageAttributeName, params);
+};
+
+module.exports = {
+  /**
+   * Given a doc, replace the parent's lineage
+   *
+   * @param {Object} doc A CouchDB document containing a parent lineage (eg. parent.parent._id)
+   * @param {Object} params
+   * @param {Object} params.replaceWith The new hierarchy { parent: { _id: 'parent', parent: { _id: 'grandparent' } }
+   * @param {string} params.startingFromId Only the part of the lineage "after" this id will be replaced
+   * @param {boolean} params.merge When true, startingFromId is replaced and when false, startingFromId's parent is
+   * replaced
+   */
+  replaceParentLineage: (doc, params) => {
+    return replaceLineage(doc, 'parent', params);
+  },
+
+  /**
+   * Given a doc, replace the contact's lineage
+   *
+   * @param {Object} doc A CouchDB document containing a contact lineage (eg. contact.parent._id)
+   * @param {Object} params
+   * @param {Object} params.replaceWith The new hierarchy { parent: { _id: 'parent', parent: { _id: 'grandparent' } }
+   * @param {string} params.startingFromId Only the part of the lineage "after" this id will be replaced
+   * @param {boolean} params.merge When true, startingFromId is replaced and when false, startingFromId's parent is
+   * replaced
+   */
+  replaceContactLineage: (doc, params) => {
+    return replaceLineage(doc, 'contact', params);
+  },
+};
diff --git a/api/tests/mocha/services/hierarchy/lineage-manipulation.spec.js b/api/tests/mocha/services/hierarchy/lineage-manipulation.spec.js
new file mode 100644
index 00000000000..837e7530475
--- /dev/null
+++ b/api/tests/mocha/services/hierarchy/lineage-manipulation.spec.js
@@ -0,0 +1,61 @@
+const { expect } = require('chai');
+const {
+  createLineageFromDoc,
+  pluckIdsFromLineage,
+  replaceParentLineage,
+  replaceContactLineage,
+} = require('../../../../src/services/hierarchy/lineage-manipulation');
+
+describe('hierarchy/lineage-manipulation', () => {
+  describe('createLineageFromDoc', () => {
+    it('returns undefined for a falsy doc', () => {
+      expect(createLineageFromDoc(undefined)).to.equal(undefined);
+      expect(createLineageFromDoc(null)).to.equal(undefined);
+    });
+
+    it('builds a lineage stub carrying the id and the existing parent chain', () => {
+      const doc = { _id: 'destination', parent: { _id: 'district', parent: { _id: 'root' } }, name: 'Dest' };
+
+      const lineage = createLineageFromDoc(doc);
+
+      expect(lineage).to.deep.equal({
+        _id: 'destination',
+        parent: { _id: 'district', parent: { _id: 'root' } },
+      });
+      // Does not carry over unrelated fields such as name.
+      expect(lineage).to.not.have.property('name');
+    });
+
+    it('leaves parent undefined for a top-level doc', () => {
+      const lineage = createLineageFromDoc({ _id: 'top' });
+
+      expect(lineage).to.deep.equal({ _id: 'top', parent: undefined });
+    });
+  });
+
+  describe('pluckIdsFromLineage', () => {
+    it('returns an empty array for a falsy lineage', () => {
+      expect(pluckIdsFromLineage(undefined)).to.deep.equal([]);
+      expect(pluckIdsFromLineage(null)).to.deep.equal([]);
+    });
+
+    it('collects ids from the lineage root downwards', () => {
+      const lineage = { _id: 'a', parent: { _id: 'b', parent: { _id: 'c' } } };
+
+      expect(pluckIdsFromLineage(lineage)).to.deep.equal(['a', 'b', 'c']);
+    });
+
+    it('appends to a provided results array', () => {
+      const lineage = { _id: 'b', parent: { _id: 'c' } };
+
+      expect(pluckIdsFromLineage(lineage, ['a'])).to.deep.equal(['a', 'b', 'c']);
+    });
+  });
+
+  describe('re-exported replace-lineage helpers', () => {
+    it('re-exports replaceParentLineage and replaceContactLineage', () => {
+      expect(replaceParentLineage).to.be.a('function');
+      expect(replaceContactLineage).to.be.a('function');
+    });
+  });
+});
diff --git a/api/tests/mocha/services/hierarchy/replace-lineage.spec.js b/api/tests/mocha/services/hierarchy/replace-lineage.spec.js
new file mode 100644
index 00000000000..571db276733
--- /dev/null
+++ b/api/tests/mocha/services/hierarchy/replace-lineage.spec.js
@@ -0,0 +1,77 @@
+const { expect } = require('chai');
+const {
+  replaceParentLineage,
+  replaceContactLineage,
+} = require('../../../../src/services/hierarchy/replace-lineage');
+
+describe('hierarchy/replace-lineage', () => {
+  const newHierarchy = { _id: 'new-parent', parent: { _id: 'new-grandparent' } };
+
+  describe('replaceParentLineage', () => {
+    it('replaces the entire parent lineage when no startingFromId is given', () => {
+      const doc = { _id: 'doc', parent: { _id: 'old-parent', parent: { _id: 'old-grandparent' } } };
+
+      const changed = replaceParentLineage(doc, { replaceWith: newHierarchy });
+
+      expect(changed).to.equal(true);
+      expect(doc.parent).to.deep.equal(newHierarchy);
+    });
+
+    it('replaces the lineage after the matching ancestor (move variant)', () => {
+      const doc = {
+        _id: 'doc',
+        parent: { _id: 'child', parent: { _id: 'source', parent: { _id: 'old-grandparent' } } },
+      };
+
+      const changed = replaceParentLineage(doc, { startingFromId: 'source', replaceWith: newHierarchy });
+
+      expect(changed).to.equal(true);
+      // 'source' is preserved; everything above it is replaced.
+      expect(doc.parent.parent._id).to.equal('source');
+      expect(doc.parent.parent.parent).to.deep.equal(newHierarchy);
+    });
+
+    it('returns false when startingFromId is not present in the lineage', () => {
+      const doc = { _id: 'doc', parent: { _id: 'old-parent', parent: { _id: 'old-grandparent' } } };
+
+      const changed = replaceParentLineage(doc, { startingFromId: 'absent', replaceWith: newHierarchy });
+
+      expect(changed).to.equal(false);
+      expect(doc.parent).to.deep.equal({ _id: 'old-parent', parent: { _id: 'old-grandparent' } });
+    });
+
+    it('clears the lineage when replaceWith is falsy', () => {
+      const doc = { _id: 'doc', parent: { _id: 'old-parent' } };
+
+      const changed = replaceParentLineage(doc, { replaceWith: undefined });
+
+      expect(changed).to.equal(true);
+      expect(doc.parent).to.equal(undefined);
+    });
+  });
+
+  describe('replaceContactLineage', () => {
+    it('replaces the entire contact lineage when no startingFromId is given', () => {
+      const doc = { _id: 'place', contact: { _id: 'old-contact', parent: { _id: 'old-parent' } } };
+
+      const changed = replaceContactLineage(doc, { replaceWith: newHierarchy });
+
+      expect(changed).to.equal(true);
+      expect(doc.contact).to.deep.equal(newHierarchy);
+    });
+
+    it('replaces the lineage starting from the matching id in merge mode', () => {
+      const doc = { _id: 'place', contact: { _id: 'source', parent: { _id: 'old-parent' } } };
+
+      const changed = replaceContactLineage(doc, {
+        startingFromId: 'source',
+        replaceWith: newHierarchy,
+        merge: true,
+      });
+
+      expect(changed).to.equal(true);
+      // In merge mode the matching id itself is replaced.
+      expect(doc.contact).to.deep.equal(newHierarchy);
+    });
+  });
+});