Stay-at-home mom refuses to watch sister's kids, 'she has no other options.' AITA?

"AITA for refusing to watch my sister's kids despite her having no other options?"

So for some context, my sister (25y) and I (23y) both live together under our dad's roof. My sister has three kids. A 7mo baby, a 4 yo and a 6 yo. The two kids have a different dad than the baby that they both live with during the school year. My sister keeps them during the summer.

This is a relatively new agreement, made around the time they finally filed for divorce around a half a year to a year ago. Basically long enough she should've come up with a plan but not long enough for her to have experienced taking care of her two kids with her now having a job and a baby.

She does have the baby in daycare, but as for her other two kids she cannot afford to put them in daycare or summer camp or what have you. Her schedule also conflicts with the daycare schedule meaning that she works Saturdays and the daycare is closed Saturday.

Most of the time this means she's calling our dad to come get the baby and take care of her for a while. I am a SAHM (stay-at-home mom). I basically run our household, I have an 18 mo toddler I care for at home and my partner (who also lives with us) works a varied schedule. My dad works a varied schedule as well but both him and my partner do manual labor.

Now. To the meat and potatoes. I'm getting stuck with babysitting duty for her two kids. We honestly tried to work things out but I told her I didn't want to care for them while she worked the entire summer because they're chaotic gremlins and I am a high strung individual as it is.

The first week was a lot easier because of the varying schedule of my partner and father (plus we had family visiting) so they were always being watched/entertained by someone. They need constant adult supervision or else they turn into tasmanian devils.

I told my sister that she needed to find other arrangements since we're all hitting burnout, but even I'm at a loss for what she can do. I'm stuck between "that's not my problem" and "I wouldn't know what to do either." But I don't want to continue to risk my sanity, so I bowed out today.

My dad did too and they got miffy with each other over it. She decided to take the day off and come care for her kids, but I have no idea what she's gonna do tomorrow. Either way, I feel bad, and I must know. AITA?

Here's what top commenters had to say about this one:

disgruntledbunni said:

A phrase I live by. "A lack of planning on your part doesn't constitute an emergency on my part." The situation sucks and is hard for those kids and her probably, but this situation is her own doing and she should request child support from the father to assist with daycare during her split custody. That's who's responsibility it is, the parents, not you. NTA.

Much_Injury_8180 said:

Your poor dad. You and your sister should be working on moving out of his home with your kids. Sounds like it is chaos now. Time for you both to grow up.

WolfGoddess77 said:

NTA. There was no harm in her asking if you could watch them, but she should have respected your answer when you said no. You being a stay-at-home parent does not equal 'free babysitting'.

Her kids are old enough now to get into all kinds of trouble, and with a house to look after and your own toddler, I can't imagine trying to keep an eye on two other kids that you always have to keep a close watch on.

PandaCotton said:

NTA. Your sister needs to find long-term, stable childcare for her children. What you're doing is a favor, not an obligation. And you shouldn't do it at the expense of your mental health or your family.

Consistent-Pickle-88 said:

NTA, she shouldn’t have had the 3rd child when she didn’t have a plan on caring for the older 2 kids. And why does she have a 7 month old baby with another man when she and her ex-husband filed for divorce 6-12 months ago? I’d love to know the backstory on that. Anyway, it’s messy timing and an all around messy situation.

toredditornotwwyd said:

NTA but clearly you should move out. Your sister’s kids are 100% not your responsibility. This sounds like hell for your poor dad. Can you get part time work on the weekends to help with saving to get out? My partner is staying at home dad right now with 1 kid & this is what he does to contribute to our expenses & savings.