[SR-Users] Custom header on reply is removed on t_relay

Hello All, We have a Kamailio proxy (P1) and a custom client (A). Calls are working reliably with A communicating directly with P1. When A sends INVITE to P1, in some cases, we insert a custom header ‘X-Routing’ in the reply. Now, testing with a new, additional proxy (P2) between these two: A -> P2 -> P1 A sends INVITE via P2 to P1, P1 replies include X-Routing header field (confirmed by logging message buffer received from P1 by P2). However, the reply relayed from P2 to A does not contain the custom header. P2’s reply_route block only contains logging code and I’ve checked for calls to remove_hf. I can’t find documentation or code to explain why the header is omitted. Is there a module config parameter that I can set to preserve custom headers? Any suggestions welcome! Regards, Dave Wilson.