If you want to merge it into your collection, that can be done fairly easy.

Create a Backup of her collection. Then restore it in your collection, but not the entire collection, only specific profiles, then select all profiles (lengthy process maybe, but it gets the job done).

Just to be sure, create a Backup of your collection before doing the Restore.

Quoting ya_shin:

Quote:

Create a Backup of her collection. Then restore it in your collection, but not the entire collection, only specific profiles, then select all profiles (lengthy process maybe, but it gets the job done).

Actually it's very quick:

Select 'Restore Specific Profiles' (as ya_shin says) then just click on Select All to select them all.

I would suggest before merging you create a Tag called 'Sisters' and set it for all her profiles before doing the backup. The tag should be copied over during the merge and will make it easy to Filter and (if you want to sometime in the future) separate out the two lists again.