Solution in Manual (Chapter 8, Page 204): Ancestral Quest uses a "Merge Audit Trail." Go to Edit > Undo Merge. Unlike many programs, AQ16 allows a multi-level undo for merges performed in the current session.
: While the manual is in English, the software supports modules for over 15 languages, including Spanish, French, and German, which are often discussed in community help posts. Community & Troubleshooting Tips ancestral quest 16 manual