I can understand the desire to be with your kids, but man, this is a weird situation... The biggest danger i see, is creating a precedent: now you'll agree with this, but keep in mind, you'll raise the bar forever. What worries me is another aspect you didn't expand in your post: is this desire supposed to be a one time thing, a curiosity that needs to be satisfied or it's presented to you like a new life-style that you're supposed to agree and live with? honestly, if the second part is your answer, why bother? It's clear that you'll become a stranger and it's only a matter of time before she'll find another lonely woman who'll want to settle, meaning there will be a lot of pressure involved in bailing you out. If the first part is your answer, i do agree with you that good times easily lead to something else. Caution is advised and i'll consider holding my ground, making it clear that although you agree with satisfying her curiosity, you don't agree with this certain way of doing it and a replacement should be found.