FPS Animations and Importing them

I’m making an FPS game. I have a view model for my character’s arms and weapons. They are both independent meshes with independent skeletons.

The animators animate the arms and the guns together (gun skeleton is nested under hand bone). And I import the meshes separately.

In-game. I currently just attach the gun to the specified bone.

How can i import my animations now so that both meshes only use 1 animation asset instead of 2 animations assets one for the arms and one for the gun?