Can I change the Deco M4s to access point mode and connect them to the router (perhaps via a switch) and use it all together?

If the router is okay and helps provide the mesh network then I may as well use that instead of bypassing it and using the M4 tower near the line into my house.

How would I go about back haul connecting a second tower to the router and using WiFi to connect another (the third would be redundant for now).

Would I have to plug the M4 into a specific slot on the router? And then I can connect the switch to another port?