Mwan3, Aliases or not, policy based routing

Hi there,

"I have a router connected to two modems, both in bridge mode. I receive public IPs from both modems, one via DHCP and the other via PPPoE, and I'm using mwan3 to load balance between them"

I have a second interface on each device (wan and eth1), with private IPs, so that I can manage the two modems. However, I can only access the modems from the router. I wanted to know if there is a way to add these interfaces to the mwan3 configuration, so that I can call, for example, '192.168.20.1' or '192.168.30.1', and the router uses these interfaces for that purpose. Is it possible? How do I do it?