removing or replacing a row based on specific criteria

I have attached a sample file which contains property information. Sheet 1 Column A contains the 'ParcelNumber' which is a county identifier. Column B (imprv_id) contains specific improvement numbers related to the parcel number. Column N (calc_area) is the total area for that specific improvement. If the Parcel number is repeated (rows 2-3, 8-9, 16-17, 23-25, 30-31, and 41-42) it means multiple living area is present on the site (guest house, mother-in-law apartment,...). However they don't parse it out in a way I can work with and after spending the entire day fighting it.... What I am hoping to do (and have created a sample result on Sheet 2) is:

Results to be on Sheet 2.
1. Create two new columns in C (bld_num) and D (add_living)
2. If a parcel number does not repeat, place a 1 in column C (bld_num)
3. If a parcel number does repeat:
a) If the imprv_id (Column B) does not repeat, just number them 1, 2, ...
b) If the imprv_id (Column B) does repeat, delete the repeating row and place the calc_area (Col N) in the new column D (add_living)

The rest of the data which is present can just be copied along and I will deal with it accordingly.

I appreciate your looking and any insight you can offer. Thank you in advance.