babysit with (someone or something)

1. To look after another person's child or children in a temporary capacity. Julia will babysit with the kids on Saturday. Any chance you can babysit with Justin while I'm at parent-teacher conferences? Your sitter canceled? Don't worry, I can babysit with the kids tonight, that's not a problem.

2. To look after another person's child or children in tandem with someone else. I know you've never babysat before, so you'll babysit with Julia on Saturday. Can you please babysit with Mom on Saturday? I know she can't keep up with two toddlers on her own. You're only 12! I won't let you watch my kids unless you babysit with your older sister, got it?

3. By extension, to look after or monitor someone, something, or an animal. Can you babysit with these petri dishes and make note of any changes while I go to lunch? A: "Uncle Al is going to know you asked me to babysit with him, and he won't be happy." B: "Well, too bad, because I'm not leaving him alone!" Maggie asked me to babysit with her cat while she travels for work.