Rude Parent Picking & Choosing Time

[TinyTwigs]

I have a dcp who I got into an argument with yesterday bc god forbid I said no to her for her switching days. This family has their set hours and the still come late and pick up later then what we agreed on the schedule. I tell everyone just bc I am opened for a certain amount of time doesn't mean you are allowed to stay hear past the hours agreed on the contract. I do this bc that way when I transition new kids if needed to transition b3fore new family leaves I know I wont have an overlap in certain parts of my day so I know what hours I can take someone in. Well she is the first to come in the morning and I have to wake up early just for her and shs already late and I know shes doing this to be a pain in my ass as she will show up when she wants. I woke up early to be ready for this family and this women is just planning on waltzing in here whenever she wants. This women is taking advantage and totally abusing the situation what should I do?