Add a subrule to rule zombies named Brains…:

Whenever a zombie injures another swashbuckler in a duel, and the injured swashbuckler receives a piece of motley from that injury, the injuring zombie must roll a DICE5. On a result of 3 or greater, the injured swashbuckler adds ‘zombie’ to eir motley if e doesn’t have it already, and becomes a zombie thusly.

Also, add another subrule to rule zombies named Must feed…:

If at least 24 hours have passed since the result of the last devouring, a zombie may initiate a devouring by moving to the location of a non-zombie swashbuckler and making a post stating eir intent of feasting on the tasty innards of that swashbuckler.
Each other swashbuckler may participate in this fight to the death (or undeath) by responding to the post. Zombies may use FOR flags to declare eir participation whereas non-zombies may use AGAINST flags. When initiating, participating in or being the target of a devouring swashbucklers may not move from eir location until 24 hours have passed since the initiating zombie made the post.

When 24 hours have passed since the initiating zombie made the post, the devouring is resolved like a duel between a swashbuckler with the combined GPS of all participating zombies and a swashbuckler with the combined GPS of all participating non-zombies. The bonus the captain receives when dueling applies only to eir contribution of GPS.

If the zombies win the devouring, the targeted swashbuckler adds ‘zombie’ to eir motley and becomes a zombie. If the non-zombies win, the initiating zombie is sent to Davey Jones’ Locker.

Setting up a ‘last pirate standing’ win condition.