I hear a lot of people use the term "multifamily" interchangeably between residential and commercial properties, and correctly so, I suppose. I like to use the terms "residential multifamily" and "commercial multifamily" though to distinguish between the two since five or more units is a whole different game with different considerations, variables, processes, etc.
Triplexes seem to be the odd ball, but duplexes and fourplexes are often times located in neighborhoods with multiple others of that property type. If there are not any comps, check with some lenders about what they would value the property at, and how they would come to that number. Depending on your goals, if the property cashflows significantly enough, you may be okay if you end up buying it at a higher than ideal amount; like if the seller's asking more than a lender says it's worth. (Not saying to buy it overpriced, just saying than higher cashflow can give you more wiggle room.) If the loan will be in your personal name, a traditional lender will probably put more weight on the value of the structure and land than on cashflow being generated. Unless you buy it with private/hard money, get it into your name, have it cashflow for x amount of months, then a traditional lender will be able to count the cashflow into your income and use that figure in refinancing it. In which case, depending on credit, appraisals, and such, they may or may not lend via mortgage the full amount to pay off the existing loan, but with that income being countable, it may open up some other options. Maybe a personal loan or line of credit you can use to pay the original loan down enough for the mortgage to cover it.
Hope what you're looking at is a good deal and you're able to get it. Keep us posted with what happens.
