I should've separated my first 3 sentences from my 2nd three sentences.

Last, can I add that agreement in the purchase contract or does that have to be a separate promissory note? 

For 2+, I pay water and they pay the rest because electric and gas are separately metered, and internet etc. is at their discretion.

We offered on it 3 separate times and it wasn't until the 3rd time that we actually got our offer accepted.

I will like to carve out a separate unit about 700 square feet with a separate entrance.Can anyone refer an architect and or share their experience on a similar projects.TIA

It does not have to be financial, it coujld be also emotional and they might feel relieved selling it to you.

I want to separate the vacation home from my personal assets.

My architect and I sent them over assembly bill No 811 on ADUs and mentioned that the looks to be in violation of the bill quoting the following:"Accessory dwelling units shall not be considered by a local agency, special district, or water corporation to bea new residential use for purposes of calculating connection fees or capacity charges for utilities, including waterand sewer service, unless the accessory dwelling unit was constructed with a new single-family dwelling"They responded saying that this didn't apply to the ADU and quoted the following"(B) For an accessory dwelling unit that is not described in subparagraph (A) of paragraph (1) of subdivision (e), alocal agency, special district, or water corporation may require a new or separate utility connection directlybetween the accessory dwelling unit and the utility.

Makes it difficult to get accurate value because of small sample size.Some infoLocation, affluent west shore suburb of Harrisburg, low crime,  family oriented neighborhoodRanch style, 2400 Square Feet total, everything updated by hvac system (works fine)Each unit has 2 bed 1.5 bath, one is 1400 sq other is 1000Rent is 1450 one side, 1500 the other, renters pay all utilitiesInsurance, maintenance, and yard upkeep total 3000 a yearGood renter clientele, most are doctors or nurses, close local hospitalsBoth have separate driveway and yard  Located in well of neighboorhood in low tax hampden township, taxes are 3500 a yearThe duplex was grandfathered, out of the 400+ houses in the  development, there are only 5 multifamilies. 4 houses down the street sold for between 380-400k in the last 4 months.

The only scenarios where I would include the utilities would be a STR or perhaps a house hack where you cant separate the utilities.