How to MPro Mesh between 2 EX5601-T0

Hello I have an ISP Provided EX5601-TO, and a WX5600-T0 operating as a mesh wifi network.

I've purchased a second EX5601-TO (Running the same firmware as the ISP provided version… latest version). I cannot see how to add the second unit to my mesh network

Preferrably i'd like to add it as a mesh node (if that's the right term) connecting one of the spare LAN ports on the primary EX5601 to the WAN port on the secondary.

Alternatively I'd be OK with running it in Wifi Mesh mode.

Finally, if mesh is not supported directly How could i set the the secondary up as a Wireless AP (again wired back to the primary). I do want everthing to use the same SSID and to seamlessly support mobile devices moving around the house.

I know i could get a second WX5600… but a EX5601 is what i have… and it clearly has the hardware to do what i need.

I have read the userguide… but the userguide details what all the options do, not how to combine those options to do what i need.

Thanks in advance