Having trouble setting up reload animation for gun


I have made an idle animation of arms holding a pistol, this is for a first person shooter so this will go in front of the camera.

I intend to make a reload animation later, but for now this is what I have. Here’s the problem:

I get the “multiple roots” error from unreal when I import this. Even though everything is parented to one root bone, there is other controllers for other objects in the skeleton, for example, the pistol and magazine both have their own controllers. This is a problem, because when I finish my reload animation need the magazine of the gun to be able to exit the pistol and switch from being parented to the right hand, to the left hand (for it to return the magazine to the pistol). How do people generally tackle first person reloads with unreal? Should I export animations separately and parent them to each other in one animation blueprint? Also keep in mind, that the pistol itself has moving parts, and the magazine must switch parents mid-animation. While I currently do not need to do this for my idle animation, I need a skeleton capable of this for when I make the reload.

I am using 3ds Max to animate and model.

Thank you