I've already asked this in the US Amazon forum as I didn't realise there were country-specific versions. So am asking again to see if there's an answer here.
We have several Echo devices and several smart switches for Energenie/Mi|Home. Original, I configures all the Echo devices with my account and added my wife's as a second Household account. I created an account in my name on the Mi|Home website https://mihome4u.co.uk, install both the Mi|Home app and Alexa app on my phone and configured all the devices and groups so that everything works as desired. I also set up a number of IFTTT events to control the lights at sunset etc, also using my account.
Since I'm a software developer, I also looked into the Mi|Home API at https://mihome4u.co.uk/api/v1 and wrote a few test programs to see how this worked. Obviously, this also used my Mi|Home account to access the devices. I assume that the Amazon Alexa Mi|home skill uses this API, although it could use a private interface. In any event, I would expect it to be at least as capable as the API.
We then decided to install the Mi|Home and Alexa apps on my wife's phone, so she could also control things from her phone. Obviously, the Mi|home app needed to be configured with my account and this worked perfectly. It simply replicated the set up on my phone and either phone can control the devices.
When it came to configuring my wife's Alexa app however, we ran into a problem. When we went through the process of discovering all devices, it found them all, but didn't retrieve the groups, even though these are available on the Mi|Home website at https://mihome4u.co.uk/device_groups and via the API at https://mihome4u.co.uk/api/v1/device_groups/list so the Alexa app (or the Amazon back end) should be able to get them easily. We tried adding an existing group, which worked, but still didn't retrieve other existing groups.
It was at this point we discovered the serious issue in the title. Once the smart devices are discovered using another Amazon account, it locks out the devices as unresponsive from the first account. This means that I could no longer control them from my phone using Alexa and, more importantly, they could also no longer be control from the Echo devices. Since they could still be controlled from the Mi|Home app, the problem was clearly not with either the devices or the API.
After some experimentation, we found that discovering devices on my phone restore it and the Echo devices control, but then all devices were marked unresponsive on my wife's phone.
This seems to be an arbitrary restriction imposed by Amazon, since, as stated above, the Mi|Home app on both phones was fully able to control all devices at all times, so the Mi|Home account was not locked out in any way by switching devices.
Is there a way to set up two or more Alexa apps to control the same set of smart devices, since, as a software developer, I can't see any reason why there would need to be a restriction against this?
Alternatively, where to I register a request that the Alexa app be enhanced to allow this.