<human>: Summarize the given text in a few sentences.

I'm not sure what to think. My sister has moved into our mum's house and leaves at all hours of the night, leaving the responsibility of babysitting to our mum constantly. My sister has recently lost her job and can't afford to live anywhere else, so has decided to live back home. Every time the kids complain about grams, my sister tells them not to listen to her. They've started to say "you're not my mum, you can't tell me anything". 

I don't live there so have only heard this story from my mum (but I believe her, cause I know my sister) and I'm conflicted. Grams isn't their mother and shouldn't backseat parent and belittle my sister's influence on the kids (which I'm sure she does on occasion) but if my sister decides to move back in with her mother and give her the responsibility of babysitting, shouldn't she be treating her with more respect and raising her children to listen to their grandmother? 
What do you think?
<bot>: my sister and her kids are living with our mum, does mum have the right to parent my sister's kids while they're living in her house?