While babysitting your nieces and nephews can be a fun activity for a few hours, no one would agree to do it for more than that as long as the child has fully capable parents. Babysitting is not the same as parenting, and by definition, it is an activity that can only last a certain amount of time.

So if your sister approaches you and asks you to «babysit» her kid while she goes abroad to work, she is essentially asking you to become a parent, and you are allowed to say no to that.

That is exactly the case for the sisters in the story below. Even though the baby girl has two parents, her mom is not comfortable with leaving her with her father. This led the mom to ask her sister to take care of her daughter while she travels abroad for work. 

The sister, who is not interested in becoming a third parent to her niece, insisted that the one who should be taking care of her is the father. Apparently, that is not good enough for the mother, which led to a family dispute.