I know that a spine project can have multiple skeletons but I didn't use it that much except when need to copy stuff from other projects.
Now I have a situation. I have a rider character(C) consist of a human(A) and an animal(B). Both the animal and the human rider are also standalone character. Thus there are total 3 characters from these two set of image. The riding version will share the rigging and some of the animations from standalone versions. I think I should rig and animate them in a single project especially for riding related animations. However, my guess is that it may not be possible to pin the human to the seat across skeletons. The animations in two skeletons are also handled separately. I cannot animate an attack animation involving both skeleton. I wonder what is the general usage of having multiple skeletons in a single spine project? It seems not suitable for my situation.
What is the best practice for situation like this (A, B and C=A+B)? My current plan is to rig them in a single skeleton for the combined character (C). After that I clone the project and remove unused stuff to make standalone A and B out of that. Would there be better way to do it?