If it is that important to you, and larger tables are available for your trip, then make an ADR for 3 (or 4) or whatever it takes, and plan to pay for an extra meal. Disney doesn't care about actual bodies per table, only the price paid for that table.
If I hadn't been able to get ADRs for my DD to eat with princesses (both CRT and Akerhaus and 1900), I'd have done this at one or more places. It just depends on how important a priority it is to you!