AnimMontage on different groups

Has anyone manage to get multiple montage to play together using different group?

The DefaultGroup.DefaultSlot bug seems to be absolutely causing me to be unable to do this.
I’d like to know if there’s a workaround on this.

The bug I’m talking about
https://answers.unrealengine.com/questions/302854/49-anim-montage-slot-are-always-placed-in-defaultg.html