How can I do this? I think it's NAT.

10.0.0.201 is within Network A (10.0.0.0/24 ) so it will not go over the WAN to the WAN of Network B (192.168.1.0/24).

Their might be a another way if you can send out a UDP packet to 10.0.0.xxx to a virtual interface on 10.0.0.0/24 say 10.0.0.254 you then do a NAT rule to the WAN of Network B and routing rule to SNAT from Network A WAN of the traffic.

Then Network B NAT to 192.168.1.7

The virtual interface way would work as long as you don't have a device with 10.0.0.201

So Network A virtual interface 10.0.0.201 on 10.0.0.0/24

NAT

incoming interface like LAN1

external IP User Defined 10.0.0.201

internal IP User Defined the WAN of Network B

port mapping the port its sending out to.

Routing

incoming interface

member like LAN1

service the port 10.0.0.201 is sending

next-hop

type interface

interface like WAN1

source network address translation outgoing-interface

on Network B

NAT

incoming interface like WAN1

external IP WAN1 address object interface

internal IP User Defined 192.168.1.7

port mapping the port its sending out to.