It's a simple enough sounding suggestion.

When you and a group of people do a map, you have a chance to get into the Canals.

When the group goes into the Canals, there should be a prompt for the owner of the map where they get to pick if it's greed for everyone but map owner or everyone can roll greed.

I'm mainly saying this from the very few rando groups I've been in recently, since I usually don't have enough people I know online at once to do maps, and there's a few people out there taking the loot and running, and we know that SE can not get any items back for us, so give the players more control on how this goes.

Also: The only loot that wouldn't be part of the rule, is all the random loot that people get anyways (Gil/materia/ect) from opening a chest/bag.