copy packet to another network card in linux

I have two or more computers running linux. One with wireless, and want to give the others wireless access by routing the traffic on the first.

I already wrote a TARGET module for iptables to change IP destination.
For example, if wlan0 is 192.168.0.1, wlan1 is 192.168.1.1, I change every packets' IP destination to 192.168.1.1, but it's not working!!
wlan1 didn't receive anything(checksum is correct). Checking /proc/sys/net/ipv4/ip_forward is 1.

I split a video stream into 2 path(load sharing), 1st path end at wlan0, 2nd end at wlan1, wlan0 and wlan1 are in the same PC. But I can't combine these 2 stream together, because the video looks not smooth.

So, I try to copy wlan1's packet to wlan0. Could someone give me a hand? Thanks