I did this recently with the roam. I opened the app at the new location and it reported a network problem. There was an option to update network settings which I did and then it worked. 
when I returned home the roam seamlessly connected to the original wifi network and that was that. 
I believe it can store multiple networks. 

I would do these three steps…

1. Whilst still at your Home ‘A’, simply add a mobile Hotspot (WiFi = iPhone-Hotspot) to the Sonos setup via ‘Update Networks’ in the Sonos App Network settings.
2. Then transport Sonos Move/Roam etc; to Home ‘B’. When there, first connect the Sonos controller device (an iPad for example) and the Move/Roam speakers to your mobile Hotspot (WiFi = iPhone-Hotspot)
3. Next add the (now in range) Home ‘B’ WiFi to the setup via ‘Update Networks’ in the Sonos Controller App and all will then work on the new WiFi.

Note: that ‘post’ transfer to Home ‘B’ WiFi, you just switch off the mobile WiFi hotspot and then connect mobile controller (iPad) to the Home ‘B’ WiFi.

Anybody else try this method? I am wary of disturbing the network connection of the stationary sonos devices, when updating my network settings. Also I do this (move to another network, temporarily) several times (to different networks each time) am I eventually going to overload the system? 

You can store upto 16 networks on your Sonos portable devices.. I have several networks that I use. Each network is saved in the Sonos App ‘Network Settings’ (as shown in screenshot) and if you select any of them, you will see there is the option to remove the chosen network.