Puzzles in making root motion animation

Hi guys, I have been using the assets on the marketplace for a long time, the root motion doesn’t seem to be a problem before, but recently when I make the root motion animation by myself I found that it’s very difficult to make root motion in 3ds max by bip (cat bone).
If I need to export root motion animation to UE4, I need to move the root bone firstly and then adjust the pose and this make me more difficult to make good animation.So now I wrote a max script that I would make a good animation without motion of root-bone, then I transform the pos and rotation of bip-bone to root-bone and It caused a big problem which rotate the IK of the foot and that does not what I want.So I want to ask you guys about how can I make good root motion animation in a simple way without concerning about the root-bone? Thanks in advance.