My nanny wants a 3way with my wife [MFF]

For sometime my sons nanny [F20] has been subtly and not so subtly letting me know she likes me. For example at least once a week I’ll come home and she’ll have her bra off on the couch and say “whoops I meant to put that back on but forgot” but now she is more like it’s nothing you haven’t seen before. Another time she was trying on dresses in front of my wife and I [M30/F29] and instead of going and changing in the bathroom so got naked right in front of us. There was a time when I was driving with her and she put her hand on my leg and massaged it, I had a hard on and she knew it. When my wife is home and my kid is sleeping my nanny sleeps and cuddles my wife.

There are other instances of this kind of behavior but recently she has been hinting to me and my wife about a three way and I’m not sure how to initiate. Any advice? Has anyone else experienced this?