With the holidays coming up I think that creating private collections would be incredibly valuable to ensure that any gifts we might be printing stay a secret. This sort of website feature would be incredibly valuable as it would allow us some semblance of privacy in our creation of things to improve our lives.
It would be great, but sadly, a new feature is something that we don't see here for years. I recommend you to look for the same 3D models in Printables, which is similar to Thingiverse in some way, and it have private collections.
Actually, I am kinda jealous that you have family members that are in your Thingiverse account to begin with and have a need to make it private!
If the family members use the same account, a private collection would not help :)
Exactly, but just nice you have family members that are into your hobby in the first place!