the usual trick is to change the wake word on one of the two devices (I don't think non-Amazon devices can change the wake word or doe drop-in and maybe one other feature). I'm not sure what a Beam is, other than it must have a screen and you can watch TV on it. The Show/Show2 might not satisfy her TV watching, but it can be handy for kitchen use.
side note: non-Amazon Alexas can't do everything an Amazon made one can do.
It's a reason I don't even look at those kind of products. I'd rather a product work WITH my echo network, not try to do what they do in a haphazard or redundant way. I think that's why Amazon made the microwave and clock, to show manufacturers a different way to think.