just chat to her. find out as much as you can about what sort of person she is like, what she is looking for in a job, what she liked about previous jobs and what didn't work so well for her. Don't ask leading questions, leave them openended.
good questions: why did you leave your last job? one before that? and one before that? answers can be quite telling.
If there are any particularly short or particularly long jobs, question her on those.
Ask what crises (health, accident, otherwise) she had encountered in her career, and how she dealt with them.
Ask how she would deal with eg a child who wouldn't eat dinner etc\ to see whether she is a hitler or what. If she starts in a vein you don't like on any subject, don't let her know you don't like it, encourage her to talk more by asking another non-leading question. Eg if she says "I'm very particular about x, won't stand any nonsense", say "and so how would you deal with it if x happened".
Make sure you tell her about your job honestly (eg if you are home late 1ce or 2ce a month, tell her that this can happen). If DS1 regularly acts like a fruit loop, then it is good that it happens in the interview, see how she copes.
Leave her to interact with children while you go to the loo or make coffee or something. She should be chatting to them or on the floor or something when you get back.,
Just go with your gut.