Many owners I have dealt with especially on single family homes do not even realize they had a separate parcel that may be able to be sold. This is because often the adjacent parcel has over the years melted into the Subjects lot by things like fencing the entire perimeter, building shops, detached garages , game courts etc. The older the property and the longer people live in it the less likely anything will ever be done. Also when one is listed often buyers just see the entire two parcels together and think they are getting one big over-sized lot and that what attracted them anyway. The Realtor also often does not even know it could be an-issue and so most MLS in my area say comments like hey look at this gem only $450,000 and owner will include parcel-2 for only an-additional $20,000. Now the buyer-borrower goes to his/her lender and the loan officer says sure no problem, have the sales contract completed at $470,000 and we can simply have escrow draw up a new deed including both subject and adjacent parcel. When appraiser gets order he/she will analyze the SC and understand the OMV includes the entire parcel as a whole. When he she does their selection of comparable's you look for sales to bracket the subjects total lot size. I had one where the combined total was like 18,000 Sq.Ft. so I found 6 sales comparable's that were on lot sizes that were between 12,000 to 18,000 Square feet after all was said and done based on lot size adjustments the market indicated buyers would pay anywhere between $15,000 to $25,000 for the additional larger lot size. So there you go no reason to get into some wacky esoteric H & B use analyses the market determined the H & B use and that was adding the additional separate parcel and placing one Fannie blanket mortgage was the best way to go for everyone.
My H & B use analyses was the same as the buyers and sellers and the market being buyers and sellers provided hard core proof- Otherwise the owner would have kept the separate parcel and the new buyer would not have wanted to pay an-extra $20,000 for it. NOW I KNOW J GRANT says financing has nothing to do with these issues but that extra $20,000 inclusded in one loan at 4% for 30 year amortized over 30 years only cost the new buyer an-additional $96.93 per-month. P.S both parcels were zoned the same and neighbor hood and market was all single family homes.