> ## Documentation Index
> Fetch the complete documentation index at: https://developer.lemlist.com/llms.txt
> Use this file to discover all available pages before exploring further.

> Merges up to 10 lemlist companies into one survivor, moving everything attached to the deleted companies onto it.

# Merge companies

Merges up to 10 lemlist companies into one. The survivor (`primaryId`) keeps its id and every value it holds; its **empty** fields are filled from the other companies, which are then deleted. A value the survivor already has is never overwritten.

Companies are addressed by their lemlist id (`cpn_xxx`).

## What moves to the survivor

* Contacts, activities, tasks and list memberships of every deleted company.
* When a CRM is connected, the survivor keeps its CRM link, or adopts the first linked company's when it has none, and receives the merged values there. lemlist never merges or deletes anything in the CRM itself: the other companys' CRM records stay in the CRM, unlinked from lemlist. Merge them CRM-side too, or a later CRM import may recreate the duplicate.

## Partial runs — `success: true` does not mean complete

The companies are folded into the survivor one at a time and the run **stops at the first failure**. The response is still `200`: `mergedIds` lists what went through, `remainingIds` what still exists — fix the cause and call again with the remaining ids. A failure on the very first fold returns an error instead, and nothing was written.

<Warning>
  There is no undo. Once merged, the secondary companies are deleted and only the survivor remains.
</Warning>