<human>: Let me see if I can explain this clearly. I had a child with my high school girlfriend. We broke up before my daughter was born, but we remain cordial enough to make it work. Five years later, she had another child with a different guy. 

I am frustrated because my parents were asked to watch this other child while her mom is at a work party this weekend (meanwhile I'll have my daughter). My parents, who are very kind, have agreed.

This is not the first time they've watched her either, and I feel like them being asked to watch this child is so inappropriate. I am upset with baby mama, and am considering saying something to her, because it seems to me that she is taking advantage of my parents. As a small side note, she mentioned to me that she might be at her work party a little later than she planned since she doesn't want to be the first to leave as it might be considered "rude." This made me even more angry because it makes my parents look like mere afterthoughts.

Am I wrong to be upset? I know this sounds awful, but I don't want to encourage her to keep having more babies that she can hand off to whomever, whenever. Meanwhile, when I expressed these concerns to my parents, they said they consider the child a member of our family. But I feel like the more they keep agreeing to watch her, the more comfortable her mom will be in asking.

Could you distill the essence of the text into 1-3 sentences?
<bot>: Concerned that my baby mama keeps asking my parents to watch my daughter's half sister (her child with another man).