My wife is going for ziyarat for 10 days and her divorced sister is living with us since few months and during my wife’s absence, she will take care of my kids. I will also stay in the home. So my question is, since we are na mehram. Is it haraam to live in the same home?
Please note we have a separate bedroom where I would be sleeping alone and she would be sleeping with my kids.

As long as you two are not alone at any time in the house it is not haraam