GridGraph A* : how to verify if a point is attainable and how to use different graphs for different agents

Hi there :)

I'm using Aron Granberg's A* pathfinding and I currently have a grid graph setup that allows ai agents to walk around the map and avoid obstacles as intended.

Next task is to separate agents between those who can travel ground and water, those who can either travel ground or water exclusively, and those who can fly. For this purpose, I am currently looking towards multiple graphs and "assigning" different agent to use a specific graph and not others. Is it possible ?

Also, I have a somewhat simpler question in relation to this. I would like to verify if the GoTo point I assign to the AIFollow (script provided by Aron Granberg's A*) is attainable by the agent. This is a noob question but I don't know where to look for the information. Is there some callback or something likely in the Seeker script that can return if the intended path is valid ?

I hope my questions are understandable and will appreciate any clues or solutions, thanks in advance !