Extend network with multiple routers

I am looking to extend our wifi network so it better covers the rooms we need it in. We've setup a wifi extender, but the service gets really spotty in rooms furthest from the main wifi router. Running ethernet cable to extend the network is difficult due to the building construction.

However, the cable MPOE is close to the spaces that need better wifi coverage. Can we add a second cable modem and connect a wifi router to it and have that second router join the existing network? This means that we will have two cable modems and two wifi routers making one large network.