I have a situation where I would like to have a single entity (Site) that potentially draws from up to three different tables. Lame I know, but it is what I've got to work with.

We have a Sites table that is maintained by a State entity and I can't modify it. However the application I'm working on requires this data and needs to be able to add sites. Unfortunately at this time I can't just add data to this table and as such I need my own sites table.

I also need to be able to allow the user to search both sets of data and present results as if they were all one.

What is the "best" way to approach this? A wrapper entity that has several properties in it referring to each table/type? Or is there a way to aggregate these tables into one collection?

I was also thinking sub-class, but I was sure how to go about this. All the sites(regardless of which table) have common data, but there are also differences.