IMQ ingress & SNAT

I try to share my connection for two boxes. So i did SNAT on my box for my friend.
Question is how to use IMQ ingress with SNATed connections?
When i try to use IMQ device in PREROUTING and mark connections for my friend, they aren't SNATed back yet, so i can't use iptables -t mangle -A PREROUTING -d my_friend_ip -j MARK

Is there any other way to do this?

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