[Users] heders in route & failure_route blocks

hello, I want to add Remote-Party-ID header in route block and change it in failure_route block. the problem is that after the failure_route block the message sent out has two Remote-Party-ID headers. in failure_route I am using remove_hf("Remote-Party-ID") scenario: original invite has no Remote-Party-ID header in route block I use: remove_hf("Remote-Party-ID"); append_rpid_hf("<", ">;party=calling;privacy=full") in failure_route block I use: remove_hf("Remote-Party-ID"); append_rpid_hf("<", ">;party=calling;privacy=off") the invite sent out after failure_route block has two Remote-Party-ID headers, one with privacy=full and another with privacy=off. is there a way to correct the problem ? from what I understand the failure_route block works on a copy of the original message, but the original message has no Remote-Party-ID header, so why the header from the route block is still visible ? on the other hand if the header added from the route block is visible why is it no seen by the remove_hf function ? thanks, Razvan Radu