In-law help, or lack there of... Vent

I live in the state that my husband is basically from. He has his aunt, 2 cousins and his cousins kids here. His aunt is always willing to brake her back for his cousin and her kids but when it comes to my kids I feel like they are treated like the terrible step kids. The last 2 days all of our kids have been out of school due to flooding and we asked his aunt to watch them while we both work (possibly 4-5 hours tops). For the last 2 days, while I was at work I've gotten calls asking "when are you getting off?" or "how much longer are you gonna be?". I don't get it. If you don't want to do something why say yes?! I honestly don't get it.

Oh BTW, his cousin has 4 kids ages (1-9) and I have 3 year old twins.