Hello everyone and sorry for the English "google translate" :-)

I created a site to site VPN with two ER605s, the connection between the sites is correctly routed and from the sites I can open the web interface of the two routers.
The LAN topology is as follows:
Site 01 WAN Router 192.168.1.254 with Gateway 192.168.1.1 connected correctly
LAN Site 01 192.168.0.x / 24
Site 02 WAN Router 192.168.1.253 with Gateway 192.168.1.1 connected correctly
LAN Site 02 192.168.2.x / 24
The clients on the two sites, if connected to the LAN ports of the switch, assume the addresses in DHCP and browse quietly and share resources with each other.
The problem is when you have to share resources on the computers between the two sites, they hardly see each other.
Before making tests that can compromise the functionality of the LANs, I would like to ask: can I solve the problem by creating port forwarding rules?
If with port forwarding I solve for individual IPs, how can I solve with the clients that would be added later?
Thanks in advance.