>>408828306
For simplicity consider having a single parent bone with two tit bones inside it, otherwise you would need one Physbone component for each tit, instead of a single one that controls both.
By default the Physbones component will ignore joints with multiple children, so setting the common parent as the root will make each child behave the same as if they each were set to the root of their own Physbones component.
Otherwise just weight paint your tit bones and you're good to go yeah.