I've seen several references to "partnerships" as a way to co-own a glider. I think having one or more "pllllartners" is a great way to gain access to a glider with higher performance and/or in better condition. But I would use that as a general term and not as a specific legal mechanism.

Some sort of limited liability structure (in the old days, a C corporation; now probably a Limited Liability Corporation-LLC) is advisable to protect each owner as much as possible from legal/financial liability resulting from the actions of a "partner". My father helped organize a number of multi-owner groups back in the 60s and 70s and always, IIRC, set up a corporation as the owner, with each "partner" owning shares in the corporation. The world hasn't gotten less litigious in the meantime.

Chip Bearden