2 Questions about nav mesh generation

Hi guys I hope someone can help me.

First, is there some way to have areas with different nav generation settings like cell size on the same map? From what I see there is one recastnavMesh called Default so I guess you can make non default ones and link them somehow to specific nav mesh volumes?

Second, is there any way I could set up my recastNavMesh so places like these are not generated as they make ai stuck?

344721-zrzut-ekranu-2021-07-23-101210.png

Thanks!