Hi there, jbenisek,
This is largely what the highlight reel is designed to help you do. I see you've applied highlights to several of your synths, so I know that you're aware of them.
In the case of a family gathering or other special occasion where you know you will be taking personal photos all within a fairly contained area you can shoot the setting either beforehand or afterward to get a good complete model of the area where all the photos belong to the same group (100% synthy or close) and then make a version of the synth which includes the shots of family and friends into it, with a fair degree of confidence that they will nest comfortably within the rest of the photos.
This frees you up to focus on taking photos of people while they are in the moment and also pretty much guarantees that all the important photos will connect to the setting. You can then simply use the highlights for all the special photos that you wanted to share in the first place.