Let's see if I have this right. Every single port will be a separate LAN with it's own DHCP server. So the router is being used exclusively as a router and not as a switch. If this is the case, why are you creating bridges? This is the way I use my routers. I have managed switches connected to the router ports to provide the switch functionality.
As for getting one LAN to communicate with all the others, but none of the others able to communicate with each other, that is easy. Add a firewall rule that allows the desired communication, and then block everything else. Here are a couple extr4acts from one of my routers. The first allows established and related and then specifically allows my .101 LAN to access my cable internet.
add action=accept chain=forward comment=\
"Accept established and related packets" connection-state=\
established,related
add action=accept chain=forward comment=\
"Allow outbound traffic from .101 to Cable internet" in-interface=\
E2-p4_101 out-interface=E1-p2_Cable_Internet
This one is at the end of the forward chain and drops anything else.
add action=drop chain=forward comment=\
"Drop any forward packets that get this far"