I'm not sure how much this will help... I have echos at two locations (using one Amazon account) and can control lights at either location, i.e., I can turn on work lights from home, or home lights from work. I use different names to distinguish which lights are which. I am not sure how it would work in your situation. I'm assuming both of you would be able to control each other's lights, however, Wemo has the option to disable "remote" use. That may restrict the "outside" echo from controlling it, but I'm not sure. If the Wemo lights are on different accounts, that may help. I believe Echo can control the lights through accounts- you talk to echo, echo talks to amazon server, amazon server talks to Wemo server, Wemo server talks to Wemo switch- very quickly. Hope you get it figured out!