We are taking a family vacation this summer. It was to be my wife and I, our two adult children, and their "significant others". One of our adult kids recently took a new job and left the area. Thus he is unable to come with us. Because we will now have an extra bedroom my daughter asked my niece and her husband if they would like to join us for part of the week. She then asked my wife if we would mind since the couple would only be with us for three of the seven days. I am not at all happy about the added couple but my wife insists they will not interfere with our plans.
Yes, they are "family" but this was to be our immediate family not someone we see once a year. This will be the only week of vacation we will get this year. We brought "outsiders" (kids friends, cousins) along when the kids were younger and there was always some conflict.
BTW - The house a which we will be staying is owned by a friend who is loaning it to us for the week.
Your thoughts are welcome.

They have already been asked, so you would need a very good reason for un-asking them, and the possibility of conflict seems to me to not be enough. If they are well mannered adults, their presence should not be a source of conflict.

There's a big difference between having extra children around, and having extra adults.

I know that I may come off as selfish but... I like to pick the people I vacation with

That's a separate issue, it's possible that your daughter (and it's her holiday too) really likes these people and wants their company on the holiday.

Honestly, if everyone behaves, I think you'll all have a good time.

Personally, I find having someone else there often has a civilising influence, and prevents debates turning into childish "You did, I didn't, yes you did" type arguments.

I agree you can't unask them now but when the trip is over, make clear to your kids that they have to ask you in the future before they invite other people to join the group, and remind them when you next make plans.

If your daughter likes your niece and her husbands company then better you should agree to her wish, it seems your wife too enjoy their company.. you mentioned there was a conflict years ago when you brought some friend kids along on vacation.. but that was old days.. now it seems like everyone here is an adult.. shouldn't be a problem.. just realx and enjoy your well deserved vacation.

Faizer

Thanks to those who responded. The vacation never happened as dates changed and Hurricane Irene intervened.