I would think you do have the right to ask but I am one of those that was really really adamant about my kids not being around OW. Then suddenly, I just changed my mind. I told him - I really can't stop you - however, you may be very surprised when the outcome is not as expected.
My kids are hurt, angry, resentful, and more than anything want to hurt back. Unfortunately, I can talk until I am blue in the face and it is not likely to change their feelings.
So, I put the ball in his court. Guess what? He realized on his own what a colossal mistake that would be.
Ultimately you cannot stop him from having D around OW. However, you also cannot protect them from the fallout. You will have to try to help your D adjust. Beyond that it is not your concern. So if it turns out that she lets fly on your H or OW and tells them how she really feels then she does. There is a fine line between trying to protect them and also trying to let them have some independence and realize that their feelings are different and separate from yours and like it or not you don't control those either.
Hang in there! Congrats on calling the L and having them wait. Really, you could likely wait indefinitely if he has signed the house over already. I mean if you wanted to.
You might just give yourself some time to take stock and figure out what you REALLY want. The holidays are not a great time to do that IMO. You naturally feel the loss in the family more when there are so many family centered activities.
