Animation Combining

I’ve seen there is a way to apply additive bone-transforms on animation sequences in persona. That’s nice, but kinda useless in my opinion, except for very small corrections etc.

What I need to do is combine a sequence with one or more complete additive animations or poses and save the result. I know there is a record-option, but it’s inaccurate because it doesn’t stick with the original key-frames. Is there any way to achieve this?