You will have to have multiple fields which is the best method. The best method is to have a second related table with multiple records then a property could have one date or several dates. It will have more than one record in the second table if there is more than one date. I don't see where that would be a problem because you would uses a portal to list all the dates together on one layout.
Thank you. I will create a second related table and see if I can figure out a seamless connection