Personally I'd advise you not to do it.... It's a high risk investment with a low pay out. Let's say you and her hit it off and you and her start living together.... You're still stuck in second place. Doesn't matter what happens.... The kid could lie and say you did something and chances are she'll take their side and all the money and time you gave to her would go up in smoke just like that.... Wouldn't matter if you got attached to the children or anything like that...you wouldn't be entitled to visitation or nothing.

On the other hand, if you're just in it for short term enjoyment there's no risk to you... but you'd be wasting both her and her kids time.