Dilemma

K heres the breakdown:

I go back to work end of sep.

My mom always watched my daughter while my husband and I worked but now we have two kids. My daughter who is a little over 2 and my son who will be 3 months when I go back.

But my sister also has a 2 year old.

Even though my sister works from home she still has my mom watch her son randomly during the week ,which wasn’t too bad when it was just them two sometimes.

But recently my nephew has been very mean and rough with our daughter. It irritates my husband and me because we’re constantly the ones havjng to discipline both kids when my sister is over because she’s too into her phone to watch her own son. And because she doesn’t discipline him he continues to push and be rough.

Now my mom will discipline him when she’s over, but our concern is there’s gonna be times where she’s preoccupied woth the baby and not gonna be able to have her eye 100% of the toddlers. And with the two toddlers you have to be constantly watching them or the pushing starts and toys are grabbed from each other etc.

I just don’t know how to tell my mom we don’t feel comfortable with her watching our two kids of my sisters son is over there. It’s not that we don’t trust my mom ,obviously we do, she watches our kids all the time. We’re just worried it’s gonna be too much of a handful with all 3.

I don’t want my mom to think we think she’s incompetent or not a good care taker. Cuz she is! We just know how hard itsgonna be on her and don’t want her to get stressed out and don’t want our daughter to get hurt because my mom is busy feeding the baby or changing a diaper and cant catch the toddlers mischief.

Any suggestions on how to bring up our concerns without it being taken the wrong way?