You can reference as many tables as you like in an Automation. Your issue is you’re trying to insert data from a previous step, and your previous steps only reference one table.
It sounds like some record gets updated in Table A, and you want to update some other record in Table B. The only way for this to work is one of the following:
- Link your records together and use Lookups/Rollups so the update happens automatically. This is usually the solution I recommend.
- Include a field in Table A that stores the Record ID of the companion record from Table B that should be updated. Again, this is easier if you link your records together
- Include a step in your Automation to search for records in Table B that match some indicator that they should be updated when Table A’s companion record get updated. The “Update Record” step can only update one record at a time, so the “List of Record IDs” output by the Find Record step must find exactly one record for this to work, otherwise you’ll need a Script action to perform the updates.