This also allows for property owners to more easily write-off assets that get damaged/destroyed as the value of these assets is determined as part of the study.

@John Friendas  it's close to the 1% rule which is good, but I would still run the financials on it. 

@Sakib KhanRecommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a property in Class D area to Class A standards, what quality of tenant will you get?

Private funding from a relative may provide flexible terms and reduced financial risk, but formal agreements are necessary, and interest paid is deductible for you but taxable for them.Traditional investment property loans offer stability and tax benefits like deductible interest and property taxes but require larger down payments.

It would leave your net worth really skewed into one asset and class of asset. 

The seller does get benefits, but they aren't necessarily financial.

I want to give them the benefit of the doubt they are just struggling with staffing but now have seen some red flags that lead me to believe there might also be some type of deceit/fraud and possible financial trouble.

Brother B could be convinced to see things my way but has had some financial strains lately so it might be an uphill battle. 5)My mom is in memory care and did not do any end-of-life planning so my brothers and I are footing the cost of her care.

Turning a historic duplex into a high-performing asset while forcing $100k in appreciation is no small feat—seriously impressive. 

More than likely the asset will in a location where cap ex & management/operational costs are disproportionately higher and therefore your expense ratio will also have to be adjusted to a higher number.