Solutions for Applying Short Looping Animations to Long Clips in uMotion

Umotion doesn't seem to have the functionality to easily add a short, looping animation on top of a longer main animation clip. For example, if my main animation is a long sequence, and I want to overlay a shorter cyclic motion, I can add an addictive layer in umotion and insert my looping clip. But to make it fit the length of the main animation, I need to manually copy and paste it over and over. This makes it very tedious to modify the looping animation later on. Is there a better way to achieve this overlay of a short loop onto a long main clip in umotion?