I know you already know how to merge, but does anything from this Help entry help you? Would it help to signal to the other PM that you'd appreciate it if they handled the sources carefully, or left it to you?
All profiles should have one == Biography == headline and one == Sources == headline with one <references /> tag directly beneath it.
When you merge profiles, the text sections must be combined. Our merging software attempts to make this easier for you. The text from the biography section from the merged-away profile is appended to the bottom of the text from the biography section of the merged-into profile, and likewise with the sources sections.
This automatic merging is rough. Always review and edit it.
You can experiment by clicking the button to restore the original text from the merged-into profile or merged-away profile. If you do, a button will appear to re-merge the text. Don't click any of these buttons if you have made edits to the text section that you want to keep — they will replace it. Another way to view the original text of the profiles is to open them in new browser windows.
You can preview the text section before confirming the merge. Please make sure that it's worthy of your ancestor. Thank you!