Are any of the properties individually titled or is there one title covering all 4 buildings?  

We did not enter into a new lease agreement yet with the "new tenants" but we have talked about move in dates and deposits and prorated stuff. 

As a FEW examples: how do you value the individual units so the other person can "buy out" the partner. 

Start attending some local meetups and networking with individuals in the city.  

@James DanchusIn the search box above enter "J Scott's Book" or: The Book on Flipping Houses and The Book on Estimating Rehab Costs

Unless the properties are in close vicinity for easier management, I suspect they will sell individually.

There are a wealth of knowledgeable individuals on this site with many years of experience in building wealth through real estate investing who are happy to answer and help driven new guys discover the way.

Now, it can depend on a number of factors, such as: what state the property is located in, whether the new owner intends to occupy the property or not, whether the tenant is Section 8 or not, whether the tenant is related to the previous mortgage holder, whether the lease was entered into before or after the previous owner obtained the mortgage, etc. 

However I do not work with individuals who use multiple agents.

They have way to many properties to deal with them on a individual "Special Case" basis.It doesn't matter if the current owner of the property has marketable title.