How to relate entities that are not directly mapped through a navigation property

I have an obj开发者_开发百科ect that has been populated with the contents of four different related entities. However i have another entity in which i cannot include as part of the query due to it not being related in the navigation properites directly to the IQueryable table i am pulling. The entity i am trying to include is related to one of the four different entities that have been included successfully.

Is there a way to include(during db hit or afterwards) this entity as part of the overall object i am creating?

Here is an example of what my calls look like to build the CARTITEM object:

    public List<CARTITEM> ListCartItem(Guid cartId)
    {
        //Create the Entity object
        List<CARTITEM> itemInfo = null;

        using (Entities webStoreContext = new Entities())
        {
                //Invoke the query
                itemInfo = WebStoreDelegates.selectCartItems.Invoke(webStoreContext).ByCartID(cartId).ToList();

        }

        //Return the result set
        return itemInfo;
    }

here is the selectCartItems filter(Where i would normally do the includes):

        public static Func<Entities, IQueryable<CARTITEM>> selectCartItems =
    CompiledQuery.Compile<Entities, IQueryable<CARTITEM>>(
        (cart) => from c in cart.CARTITEM.Include("ITEM").Include("SHIPPINGOPTION").Include("RELATEDITEM").Include("PROMOTION")
                  select c);

from this i have my CARTITEM object. Problem is i want to include the PROMOTIONTYPE table in this object, but since the CARTIEM entity doesn't have a navigation property directly to the PROMOTIONTYPE table i get an error.

Let me know if you need any more clarification. Thanks, Billy

You can use join and if it is the same database and server it should generate the join in SQL and do it all in one call...

LinqToEnties join example