Winning: What raitchjay and Joker are referring to is the "Mixed Use Property" issue found in the definition of "dwelling".
If a dwelling is located on property used for both residential and commercial purposes the lender must decide the property’s primary purpose. The Commentary to §1003.2(f) #4 states "An institution may use any reasonable standard to determine the primary use of the property, such as by square footage or by the income generated (or income per square foot, borrower’s intent, etc.). An institution may select the standard to apply on a case-by-case basis.
If the MH is located on the same property as the commercial use property, then you have a mixed-use property. If that's true, it sounds like this would not be a dwelling for HMDA. If it's not located on the same property, then you have a dwelling secured loan replacing a dwelling secured loan - a "refinancing" for HMDA.