B.B.
With grandmas health I would have grandma be "supervisor" and other person be main care...
Pay would depend on the age of the person. If it is a child then you could get away with less than if its an adult. Also depends on the age of the child...
Do you pay grandma? Who ever does main care I would pay them the going rate... You could ask them what THEY think is reasonable... If they want the job they may lowball it...