If you want to have more requests (or offers) in your sign up than the maximum 10 allowed by the AO3 interface, you can add more fandoms in the "Optional Tags" field on the sign up form and the matching algorithm will be able to take them into account. To make it work, you need to select one fandom in the normal way and then use "Any Eligible Relationship or Character" (rather than any specific relationship tags) in the Relationship field. Then add any further fandoms in the "Optional Tags" section. We ask that people only do it a maximum once each for requests and offers.

Yuletide has had bucket offers for a long time; where FGE differs is in also having bucket requests.