platyping
Sleeping Dragon
If what you want is just for a team to be able to found on water.
Then codes only need to be done under canFoundCitiesOnWater.
Not needed to use the other section.
Then codes only need to be done under canFoundCitiesOnWater.
Not needed to use the other section.

, is in CVUnitAI::AI_promote, which does indeed try and add the promotion with the highest value to the unit.
If you want to use it for anything you want to happen it can't be a repeating tech, so you need to add a tech before it which is the one you add things to.