Updating Terrain Collider through script

Ello there, So I'm creating terrains through a script, using CreateTerrainGameObject to instantiate a 3x3 grid and then updating the terraindata and position of the grid as the player moves. This is working fine except that for some terrains(like mountains) I can walk through them as if they werent there. My assumption is that the colliders for each part of the grid are only being assigned when the "CreateTerrainGameObject" is used (inside the start function). My question is, how do I access the collider data of a piece of terrain and pass it to an existing terrain during an update?