Unity NavMesh Update Data Without Baking

Hey everyone in my game there is some peasents walking around in a landpiece. Player is able to unlock new lands(as you can guess it is a arcade idle game).

When player unlocks a land i want to make my peasents be able to walk on that new land. If i bake the map everytime a land unlocked, that is causing a pretty obvious fps drop for a second because of baking a map is really expensive function.

I created an area named _peasents. I choose the lands which peasents are walking with _peasents area. I tried to make unlocked land's area _peasents via code when it is unlocked but even if it change the area it still needs a rebake to accept changes.

I am so close to finish my game but this problem is coming with me since day 1, thanks for any suggestion or discuss.