Hi Ushah,
Many times what I do in one-to-one relationships is:
1.) Make sure there is a relationship in the DB between the two Primary Keys of the two tables.
2.) In the LLBLGen Designer, assign Fields on Related Fields. This way, your Entity in Table 1, can have Read/Write properties for columns belonging to the Entity for Table 2. Using this method, you could use one Entity for both Tables.
Hope this helps!
Ryan
PS. You can also access the other entity by doing: myReceiptLineItem = myReceipt.ReceiptLineItems