Terrain blend priority

im trying to create 3 new terrains, one is a type deep water, one is type ice beach, and the other is type ground. in the genie editor theres a lot of numbers and stuff for SLPs but i dont really think most of them do anything. blend type and blend priority seem to be the most important things. i believe i can just use the same blend type as what i want, like 80 for beach ice, and set the blend priority to a number that isnt already taken as long as im getting the 3 terrains im making in order, deep water on bottom, beach ice in middle, ground on top.

does anyone have any info on this? i havent really found any info up to date about terrain mods and most of the terrain mods ive found are just texture replacements. that would work as a last resort but getting the terrains to work as intended would be much more satisfactory.