We just bought a tenant occupied rental and there is a preexisting pool that is not part of the property.

If there is a company that has a pre-existing line of credit the line will have a provision that if there is a change of control (the company is purchased, the key management is changed) then the line is reviewed or automatically pulled.What you will get is a few years of existence plus prior credit history based on past transactions.

Your legal compliance requirements will largely depend on whether your investors are: a) active (easiest legal documents) or passive (more complex legal documents); b) accredited (easiest legal documents - No PPM required) or non-accredited (PPM/disclosure document required)c) everything is in one state – you, investors and the property (may be an easy intrastate offering exemption you could follow), or crossing state lines (usually means you have to follow the federal exemption rules, which can be costly)d) people you have a pre-existing relationship with (easiest way to raise money) or want to advertise (harder to raise money, probably need a track record with similar properties and investors). 

It could be a pre-existing non-conforming use in which the duplex existed before your zoning ordinance in which you have no issue.You really want to know definitively from the municipality how they understand the property's use with respect to zoning. 

I will say that based on my experience, it looks easier to buy a pre-existing home than building one. 

By adding in all property types, new con, pre existing, condos etc etc, and keep it segmented to JUST Luxury real estate $ levels.

Its much more economical to buy a pre existing park.

Reduced Fee ServicesWith your membership you receive a 25% discount off your provider lawyer's standard hourly rate on any legal matter not specifically covered on the plan, including pre-existing conditions.

The above issues are extremely common with all properties I buy, but what I buy are pre-existing multifamily with some meat on the bone. 

If an investor is not accredited then they MUST be sophisticated per SEC Rule 506(b) of Regulation D and you must have a pre-existing and substantiate relationship.