Is it possible to combine animations from different character rigs ?

Hello I have a question regarding character rigs and animations

Lets say I have character with full rig - head,body,arms,legs,fingers etc… in one file with its own animations - walking,running etc… and a gun and hand rig in another file - with its own animations - shoot,reload,aim etc…

My question is. Is it possible to take the hand animations from the gun file and use them with the chracter rig ?

Yes, using animation layers. Specifically, you can use masks so that certain layers only affect certain bones and/or use additive layers (as opposed to override layers) to add the relative movements of the layer to the overall motion. Note that because additive layers read animations as movements relative to the first frame, they might not always behave as expected, especially if the bones they affect aren’t being controlled by any override layers. However, once you get used to them, along with blend trees, you’ll be able to do quite a bit with the animation system.