My daughter refused all the back up plans I offered because I was the only one that could watch her children...ha ha, she played me. The other grandma lives nearby, doesn't work and is very rich...she has not once watched the boys in 18 years..I exaggerate...she watched them twice and never overnight.
Oh she gets breaks from caring for her. In fact, basically speaking, the only time the older sister see's the younger one is when she pays the rent for her once a month. The rest of the time, the younger sister is "on her own". The home where she is provides the meals for her, and other than those meals, the younger sister just lays around most of the day. At least that's what we understand.