No, you can't combine the miles, unless you are willing to pay a high fee to transfer them. Yes, you can book one way flights, and you can book tickets in anyone's name you choose. Your plan would work if you can find availability.

I recommend flying into one city and out of another (like into Paris and out of London, using the train between cities). Be sure to check less popular destinations like Brussels, and check for business class seats to at least compare the cost in points to coach.