Currently, if your lions are Hunters or Broodmothers, they cannot be put up for trade.
However.. "Secured" Lions can still be put up for trade.

You can set "All Lionesses" to Hunter through the Hunting area in Crossroads but you can't do this by cave or individually select lions and Sort them into these categories.

It really bothered me to find out that a lioness I value very highly was accidentally put on TC for as cheap as 300sb with a lion I wanted to sell.. Thankfully I caught the trade before she actually sold. These lions were in two totally separate caves and there's no way I should've accidentally added her.. but here we are. It's a mistake/oversight that could've cost me valuable project progress.

Suggestions:
- Allow caves to be "Set Cave to Hunter", "Set Cave to Secured", meaning any current and any future lions put into this cave will be assigned the roles Hunter (if applicable) and/or Secured.
- Allow the Mass-Assigning of roles to Caves, similarly to Mass-Moving. (Can also apply to individual lions)
- Add a togglable option or setting (or just outright change it) so that secured lions cannot be put for trade or transferred.
-OR- Add a togglable option or setting to "Set Cave to NOT FOR SALE", meaning any current and any future lions put into this cave cannot be put onto TC or Transferred. If they are removed from this cave, that lion can be placed onto TC/Transferred. (Can also apply to individual lions)

Will update with FAQ/Other suggestions from users. This is just a quick post before bed.