Please provide sample DDL, sample data, with INSERT statements corresponding with the sample data and desired results, so that we can properly understand what you are trying to do and provide sample code as a solution. This is all described well if you follow the first link in my signature. Without this, we are largely shooting in the dark. No one here is going to recommend that you drop or disable a FK without first understanding why.
Phil's suggestion will go a long way to not make guesses as to what may or may not work. I don't even want to offer any other advise at this point since we are dealing with bypassing a item that ensures data integrity. The order in which you insert data matters. There is a function, scope_identity(), which may or may not be helpful to you. Without knowing more as to your situation that is all I can state.
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