Ok, I think I’m finally figured it out. Haven’t tested it yet in UE4 though:
Apparently UE4 supports up to 4 layers of bones skin. So I can have lets say two layers of bones, one will be rotating bone and the other is stretch / squash.
link: What are the Bone Limitations in UE4? - Character & Animation - Unreal Engine Forums
So will try this now. I only need 2 influence layers for my ball to work properly. So far I think this is the most elegant solution and the least complicated one. Although I need to test a performance cost for having 2 influence layers.
Cheers