Question

How do I find the ID number of ancestors I wish to merge?

Answer 1

Can you tell us who would like to merge? Merging is only done between two duplicate profiles as there should only be one profile per person on WikiTree. Here is a link to merging from the Help pages: https://www.wikitree.com/wiki/Help:Merging

If this is not what you are asking, please come back and explain a bit more so we can help.

Answer 2

The ID number of each profile is shown at the top right of the page, just to the right of the 'My WikiTree' menu.  It's also in the URL your web browser is looking at.  You can propose a merge when you see two different profile IDs that represent the same person, and you can go ahead and complete it if you are Profile Manager of both profiles.