As soon as V told ILs that we bought a place, MIL said "congrats!" and also, "Do you have room for BIL to rent? Just a thought!"
I know that we'll have 3x as much space in the new place as we do here, and I know that we'll have the extra bedroom. (Of course, the bedroom is very small, and right next to the baby's room.) And I know that the extra income would be awesome.
But he wouldn't be living as a tenant in a separate apartment; he'd be sharing the house with us. I've "lived" with him before when he and V lived together and I was not impressed by his cleanliness, though I've heard that he's grown up a lot and gotten much better since then.
So is it selfish of me to say, "I just don't wanna"?

Re: MIL's latest idea
Is this the same BIL that left the fridge door cracked and ruined all the stuff in the fridge?
We had both of our brothers living with us for 1 summer, and that was enough for me. I'd do it to help out family in a pinch, but it would not be my first idea, especially not with a new born.
We'll just not tell H about this little fact, m'kay?
I vote not selfish. It's your new space and you should be able to enjoy it without worrying about housemates, even if they are family. (Congrats on the house, btw!)
That's the one!
Baby #2: Surprise BFP 9.19.12, EDD 5.24.13, natural m/c 10.19.13 at 9w
Nope not selfish at all. I'd feel the exact same way especially with a baby on the way.
By the way, have you told your families yet? I've been waiting to hear your MIL's reaction but maybe I missed something.
DON'T DO IT!
I LOVE my BIL. We get along great. He is fairly clean, in the summer he works like crazy and is never around, and STILL I hated him living with us. It is hard to have a third person living with you as a couple. When Ed does something that annoys me, I can tell him--that is how a relationship works, but when another person who is living with you and paying rent does something that annoys you (but isn't really a problem) it isn't as okay to say something...then things get weird. Add in the new baby and sleep deprivation on top of that and it seems to me like you will end up unhappy in the long run. Unless it is a huge emergency and the situation is temporary with a firm end date, I wouldn't do it.
BFP 5/2/11, missed m/c, D&C 6/13/11
BFP 12/8/11--Little Girl E Born 8/22/12
About the baby you mean?
When we told our parents about the baby... MIL said "Thank the Lord! I've been praying that you'd embrace parenthood!" -awkward. FIL jumped up and said, "Thank you!" -um, you're welcome?
My mom was not expecting the news at all, she gasped a little and took a minute to process it. I told my dad on the phone because he was in Hong Kong. It was his birthday and he sent me a very nice email a couple of days later to say that it was his best birthday ever.
Baby #2: Surprise BFP 9.19.12, EDD 5.24.13, natural m/c 10.19.13 at 9w
Yes, I meant about the baby. Your IL's response is great. I expected your MIL to say something negative. It does make me wonder why she would suggest BIL moving in since she knows you're expecting. How do you respond to a thank you, so awkward!
How sweet of your dad! So glad it went well telling both sets of parents.
I would say NO. This is your time to "nest" and be a new family with a baby. It's not time to rent a room. Unless he was in desperate straights i wouldn't do it.
Also you bought a place! what are the details. Congratulations.
The Daily Nugget
Cycle 12, IUI #1 - 33m post wash 10/15/10 = BFN
Cycle 13, IUI #2 - 15m post wash 11/16/10 = BFP, missed m/c, D&C 1/3/11
Cycle 15 - 18, IUI #3-6 = BFN
Cycle 20, IUI #7 = BFP!, missed m/c 9/14, D&C
DE-IVF Aug. 2012: ER 8/30 11R, 7M, 4F; ET 9/4 returned 2
Beta 9/18 #1-820, #2-1699, #3-7124
10/1 1st u/s measuring right on track, 125 bpm
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Cloth Diaper World
Now jumping domestically.
Well that was a crazy couple of years.
I would think that BIL wouldn't want to move in with a new baby in the house. Maybe it's just me, but I can't imagine renting a room with a newborn next door crying all the time. It's one thing when it's your baby and you know what you're in for. Has BIL ever mentioned anything or is MIL just being a pain without even thinking about it?
I vote completely unselfish. Enjoy your new house, walking around naked, sleeping on the couch, etc. Having a roommate is no fun.
I don't think the thought has even occurred to BIL, though he is looking for an apartment and roommate for the summer and beyond. He doesn't want to live alone. I think MIL just thinks it's a cute idea.
V keeps going back and forth on it. The extra income looks really attractive to him and I think he's got a bit of a rosy view on the idea of living together. But he's more or less on board with me. It occurred to him, "I do like the idea of being able to walk around in my boxers when I want," LOL.
Baby #2: Surprise BFP 9.19.12, EDD 5.24.13, natural m/c 10.19.13 at 9w