I'm not sure how to do this. I'm currently working on adding multiple configurations to my character -players will select their weapon, head, armor etc. and doing this with Skins means only 1 change can be active at a time. What was flyover describing above? Anyone know how to make this work - short of having the character made up of several different spine objects and jsons and then using skins for each? - Is there a better way?
I'm sure Flyover's way is better but that's how I chose to do it myself as I am not the most technically proficient user.
If you choose to do it my way, just keep re exporting with only one visible attachment (grouped however you have it set up, of course).
Make sure you apply a bounding box to the singular attachment or scaling will be wonky.
Use Set Time (0) with every state change (Attack, Jumping, Etc) to make sure that the animations don't desync from one another over time.
You may know all this better than me, just giving you insight into the issues I had with an avatar system.