Also from MokahTGS on CurseForge: Perhaps you could have a UI come up on right click in the air to pick the pet to summon. If you right click on a pet it adds it to the list. Sneak right click removes it from the list.

Currently this would require a complete rewrite along with packet handling on the server/client side, as well as an interface. Alternately, a specific item could be implemented that could be shift-clicked against a certain mob and it would only summon that mob.

Again, this would require NBT shenanigans.

Honestly, I won't be doing this. It's beyond my skill and desire.