The BSSID is unique per SSID, per AP. The BSSID is usually derived (usually by incrementing the last octet) from the AP MAC address, however.
So an AP MAC might be 77:99:44:EE:C4:11.
It has a wireless network called "Bob's SSID". It will have a BSSID of something like 77:99:44:EE:C4:12.
Then, the AP may be broadcasting another called "Mary's SSID", and it will have a BSSID of something like 77:99:44:EE:C4:13.
Edit: More not-well-written info on BSSIDs: https://en.wikipedia.org/wiki/Service_set_(802.11_network)
Looks like the BSSID is derived from the AP serial number by some vendors. Never seen that myself.
And then see if you can be magically transported somewhere else.
Consumer router firmware UIs, typically owned by ISPs, I'd not expect that yeah. Some don't even let you pick a WiFi band anymore and require other changes to be submitted through an ISP portal on the web somewhere (thinking of Belgium here, not sure which ISP it was)
Sure, some hacker somewhere will screw with these databases by rotating their AP MAC Address regularly but 99.9% are not going to touch it and 99.9% is good enough for location databases.
