Hi,

Merging two Odoo databases, even when running the same version, is a complex task, and there is no official one-click solution. However, various proven strategies can help you combine data intelligently depending on your needs.

1. Export / Import Selected Data (Simplest):

                         - Selectively merging Customers, Products, Sales Orders without disturbing existing data.

          -Use built-in CSV/XML export/import:

        -  Export key models (e.g., res.partner, product.template, product.product, sale.order, account.move).

        - Before import, clean and remap IDs, ensuring any references (like partner_id) are updated.

2- Multi-Company Consolidation (Alternative)

            - If the ultimate goal is combining companies rather than merging historical data:                                   - Configure one database as a multi-company instance.

                             - Migrate one DB’s data first.

                             - Then import the other DB’s customers, products, and transactions into the same company structure.

                              - Still requires export/import or scripting, but uses Odoo’s native multi-company architecture.

NOTE:-

           - Back up both databases completely using pg_dump or Odoo tools.

           - Set up a test environment and run the entire merge flow there first.

           - Never operate directly on live databases without tested backups.

Hope it helps

There is no out-of-the-box database merge functionality in Odoo.

You are probably better off by just creating a new database and re-creating your configuration in there.

What you could do alternatively, but this depends on the data in either of the databases, is to manually export from one database and import these files into the other (i.e. Contacts, Products, etc.).