The most positive family relationship in my life was with my Childless step grandad. So I'm glad that my GM took that chance. She was a wise woman and a bloody good mother, who, although born in 1911, made sure that she was always financially independent.
My Uncle, his SS, went on to be a wonderful adoptive father of three. His Wife was Widowed which makes things less complicated.
I was widowed. I am amazed at how some women ignore all the red flags and seem desperate to move men in. I've had everything from fuck buddies to a steady (6 years) BF. But wouldn't have let him move into our family home. I don't see the need.
So many women jump too quickly from moving them in to being pregnant again. Ignoring red flags.
My DD has two children. Her ex doesn't take the children overnight so her BF stays over. We know him and his family well. Her BF has pitched in when her children have had vomiting bugs, through the night. She takes her children to school and comes, back to him cleaning up and a wash put on. He's done the same when she's gone to the shops.
My GC has a medical condition and of his own accord, he read up on it and child development.
We don't do Christmas presents as Adults. But he's asked what he can get for the children. He takes note and learns about their interests. Before this he had no clue about kids tv/gaming/toys etc.
Their bio dad is a selfish prick. My bio dad was an abusive arsehole. I worked in child protection. Being a Dad doesn't mean a thing. You can't go of what type of dad they are, because often abusive men are very loving towards their bio female relatives.
So I'd say yes, but take your time. Don't live with them, in their house for many years and don't get pregnant under circumstances that you means you can't, straight away, leave, if they change. You need someone who like all different types of personalities, is tolerant, unselfish, generous and kind. Not having children, I think, is a bonus.