BF, there's a fair amount of carpooling going on, and they are always looking for more hams. They didn't have enough this year and had to have a few stations with only 1 ham when they usually have 2. You can request (and apparently often get) specific locations. The ham I worked with at Med-6 has been at that same station for 8 years straight, and the med team there hasn't changed in 6 years. So, if you can find a ham to pair with I bet they would keep you together. The ham organization is personal enough that you can email the guys directly with requests.
BTW, as a volunteer you get a cool Marathon logo sports jacket (that I never wear) like the red ones you see in the pictures above, a BAA-Marathon pin and free entry to the after-party at Fenway. I went to the after-party last night. We got to walk the warning track, take pics standing in front of the green monster score board, drink Sam Adams "26.2 Ale" and take pictures with the Sox's 3 recent World Series trophies.