Hmm. In our house, our dog sleeps in OUR room. :)
She slept in a crate next to the bed (on my side) when she was a small puppy when we first brought her home, and that is where she has stayed. Of course, we stopped closing the door to the crate, and she was free to come and go as she please---but she always seemed to 'please' to be next to my side of the bed. :)
I am not sure what I would do in your situation. My natural choice would be to let the dog choose. I mean... like you said, the dog is going to choose to be near whomever he feels attached to the most. The problem with that is that it seems to be your SD, who is not there every other week. And that could cause unnecessary stress your dog.
Maybe you could encourage the dog to sleep in your room and solve the entire thing in one shot. Because the dog is NOT a possession, but a pack/family member. And all dogs have a place in the hierarchy of the pack. Usually where a dog will choose to sleep is as close to the alpha as they are allowed to be.
ETA: Crate training will solve both of those issues. :) Our dog is not allowed on the beds (ours OR the kids'). And until I go to bed at night, she roams around and checks on the kids in their rooms. Sometimes she'll take a short nap in one of their rooms until I go to bed. It varies. Sometimes my son, sometimes my daughter. Sometimes she just pushes their door open and does a once-through of their room and comes back out. Then she will eventually make her way to our room. She is a bigger dog than you have (GSD), so she could stick her nose right up on the bed if she wanted... but she knows that it isn't her place, so she keeps it (and the rest of herself) on the floor for the most part (I do pet her from the bed as a "good night" pet once I am in bed, then she does her 3 turns in a circle and lies down).
And booting her to outside the bedroom? No biggie. What's wrong with doing that? We always close (and lock) our bedroom door for such things, and if the dog is in, it's fine. If she is out, that's fine too. No whining or anything else from her. She knows her place.
After, I'll open the door and if she's been "out" and wants to come "in" to go to sleep, she will, and usually does.
Basically, I'm just saying you could solve your issues with the dog in your room if you want to. It wouldn't be hard. But if you'd rather him sleep in your kids' rooms, then you will have the issues you currently have to solve, still.
Up to you, of course... :)