Currently I am working on my own VR interaction/grip system and this is my anim BP:
The first block contain the default hand animations, provided by the VR template. I saved this as cached pose which is basically storing that in kind of a local variable.
Second block contain the hand animations for my control box, like gripping that box, pushing buttons or moving thumb. It is basically a complete state machine just for grabbing this item, mirrored for the left hand and saved to a cached variable as well.
Third block contain blending of each animation set, depending of the grab type. If grab type enum is set to ‘Switchbox’ it will blend over from default animation and play my custom anims.
In that way you could add hundreds of state machines or single animation sequences and blend them together.