We are closing in on 60 days before our start-of-August "take your siblings to Disney" OKW stay

, and for the first time in many visits, the room request part of the planning is more important than usual for us (and a bit complicated). I need expert advice!
1) First, two members of our party are going to have some (minor) problems with walking and stairs (I'll spare you the details), and we were unable to get a "HH building" reservation. Therefore, by far, the best buildings for us would be 62, 63, or 64 (elevators plus proximity to HH), with 62 being the dream assignment. However, the OKW online check-in options make it confusing as to exactly what to ask for (although it's easy to see what NOT to ask for!). What would you suggest?
2) Second, this is our first experience with "linked" reservations (2 studios as close as possible). Even if we put the exact same online requests for both reservations, is it possible that simply doing online check-in will make our highest priority (very close studios) less likely? Can I do anything online to assure the reservations stay linked?
Thanks in advance...it's fun to post again after a long hiatus!