One way to achieve this is
- Define a tag for the SSID, e.g., “TAG1”
- Tag the AP(s) that should make that SSID available with the tag (“TAG1”)
- Define the SSID and set the SSID availability to “SSID available on some devices…”.
- Then enter the tag (“TAG1”) in the field “Only enable on devices with any of the following tags”
That should do it.