Some properties may be able to be subdivided, this depends on the location property size how the homes are situated etc. This will not be a â€œtypicalâ€ transaction and will require the assistance of a professional.
As far as how to market the property it really depends. The ability to subdivide (if possible) would lead in one direction, the size of the homes, etc may lead in a different direction. I wish there was a simple answer but I would consult with a Real Estate professional, interview 1 or more agents and see how tht can assist you so that you can make an educated choice.
First, you should hire a Professional Real Estate Agent to list and market your properties.
I would suggest listing the properties in 3 listings.......One listing for each house and one listing for both houses.