You're allowed to book additional rooms under your name. I did so recently and booked 4 rooms under my name !

You can all check in at the same time. It shouldn't be a problem and depending on the hotel, you might be able to get your benefits for all rooms. The hotel I stayed in in England gave free breakfast for all the rooms booked under my name. To get credit on the additional rooms though, is to ask that everyone's bill gets transferred to the room that you're staying in upon check out. You'll only get credit for the night you stay in your room, but you'll at least get a bigger room charge!