We have 20 acres. There are 3 of us [whom] it was willed to. One brother wants to survey and deed off each portion. Will this hurt the value?

I added punctuation and capital letters to your post to make it more readable so others will respond (and not be confused). Is my editing correct?

It might hurt if a developer wants to purchase a large area for a subdivision or superstore/parking lot. My husband's siblings divided up a large chunk of land in Arizona, and the total value of the individual chunks is not as great as the entire acreage would have been.

No way to answer that without knowing the area. Better ask a local real estate agent.