What would you do..?

[bright sparks]

I don't think this is a case of termination. I think it is just a matter of having a conversation about a mutually agreeable date and taking the lead based on what your new family needs. While nothing is a guarantee, what is a guarantee is that this family will pull this child...she has already told you as much. She has given you a vague time line so now the ball is in your court to agree on a firm date. It doesn't have to be a termination, simply state that you have a family looking for care on XX of October and that needs to be the finish date for her son. She likely wont have an issue with it, and I don't agree that this is you terming them for another family. This is you taking her directive of finishing Oct/Nov and firming up a date that works for you as a business woman.

[Lee-Bee]

I think I would just caution you to try and set a firm end date sooner than later. There is a chance they will change their mind (a few times) if they just assume their space is there space until they decide to officially leave (they technically have already changed their mind once). So right now they plan to pull him in the fall...but maybe in a couple weeks they decide to keep him in until new baby is a couple months old. Then baby is born and they decide to pull him right away. I would caution filling their space for October now but waiting until 3 weeks before to tell them.