in theory there are 65 active players so in theory there should be over 30 but i imagine not everyone will sign up, so probably 16 will play. However there will be qualifiers to get into the tournament, Seeding for this first doubles will again go on post ranks.
Seeding will be done on post rank for the first tournament just like singles was, and the post rank between the 2 players will be averaged Say if you had the 2nd and 30th in post ranked it would be averaged to 16th