Merging/Adding two animations together

I’m trying to add two animations together:

I have a single-frame sitting animation, and want to add a breathing animation to it.
There’s a forums thread with the same problem, but I don’t really understand the answer:

I tried several methods, but I can’t figure out how to do this.

So, a little more experimenting and I found a solution that seems to work:

set the base idle animation (in my case sitting) to Additive Anim Type None and change the type of the blend animation (e.g. breathing) to Local Space and Base Pose Type to Skeleton Reference

Now you can use the Apply Additive node in the Animation Blueprint. Use the idle animation as the base and the breathing animation the additive input.