How to use a control rig on multiple bones?

Hello! I’m currently using UE5 for this.

I’m trying to rig a character I Imported so that when I grab the hand and move it, the entire arm will move as well, but when I combine the bones together, I get a mess of an arm.

Basically, the shoulder, upper, lower arm and hand aren’t connecting, but when I move the hand around, the hand moves, as well as the other parts, but not in the right motion i want it in.

Any help please?

P.S. I imported this mesh from Sketchfab, the guy who made it labeled some of the body parts, but got lazy and stopped naming the rest.

Here is the skeleton tree by the way