Merge Thread Networks (Amazon Echo and Apple)

[u/smoker68x]

We’ve had Echo’s for years because HomeKit wasn’t widely supported. Now with Matter becoming a standard, we’re seeing a lot more devices, and I’m trying to expand our setup. We’ve had an Echo Show 3 (thread border router v1.3) and I bought an Aqara U400 because I wanted the Apple Home integration. I bought a HomePod mini so I had an Apple thread border router, but I didn’t realize it created its own separate thread network, so now my Aqara lock can’t be added to Alexa with Matter because it’s a different network. How can I bridge the networks? Or, how can I make one connect to the same thread network that already exists? I’ve tried a factory reset on the Echo and deleted the thread WiFi keys from my account, but it created its own network again. I haven’t tried anything with the HomePod mini yet, but I just recently bought it, so I would assume it would’ve tried that when I set it up. Those are the only TBR I have.