The secure feature is basically pointless - all it does is keep you from chasing, killing, or preserving a lion/ess. You can still sell them and lose them in a bunch of other ways.

Case in point, and my major objection:

I had two adols that were 1 year and 11 months yesterday. One was a tree adol, the other was my secured ebony daughter. They both aged up, but I only had space for one. You know who stayed? The tree adol. The ebony that I had specifically secured was the one who 'ran away' due to lack of space. Now, I understand if a secured lion runs away due to lack of food/mood. That's a game mechanic, and a core one. But if you have 2 adols aging up, and one is secured, that one should take priority and get the slot. In addition, you shouldn't be able to put them up for sale. You should have to remove the secure label before you sell them, like you have to remove it if you want to chase/kill/preserve them. Same for sending them to the Enclave.

Make secure actually keep your family safe!