how to switch users between two dns servers using iptables ?

i have two dnsmasq running on port 53 and 5053 on my ubuntu server and there is two users X and Y

X's ip :192.168.1.2

Y's ip :192.168.1.3

both have my dns server on their settings .by default they use the dnsmasq on port 53 how i can switch one of the users to second dnsmasq (on port 5053) using iptables ?