Just as a point of clarification. I don't consider the formation of ad hoc teams (without a GC account of the same name) to be necessarily a bad thing. If 4-5 people are caching together, jotting down a team name does save time and space in the logs, and if everyone indicates in their online log that it was signed as "Team Whatever" it tells the CO why a specific geocaching handle isn't in the log sheet. It's when a team starts to split up and does the 3 cache monte thing or looks for caches, separately, in complete different areas, is when I think that they're just trying to game the system.
I completely agree with you. I think that forming a "team" and some of that team goes to certain caches and others go to different caches is not cool. But if you are all together finding the caches and signing as a Team name that's okay in my book. Saves the CO from having to go replace the log because 8 or 9 finders signed in. In the instance of what the OP said though they're caching as a family. I don't see any hurt if they log a find under their team account if say only 3 out of the 4 members were present.