The Selection-Option is limited to 2 (on a SOHO) per Interface. The official supported SonicPoints in total also 2.
In some older firmware versions, for example 126.96.36.199, the SOHO Device had an option to select 16 SonicPoints on the WLAN Interface. This was a special Workset and is not officially supported.
In 188.8.131.52 and later firmware versions, this has been corrected and it now shows 2 SonicPoints.
Even if you create a additional Interface, for example X4 WLAN 172.16.31.1 and X5 WLAN 172.16.32.2 (via Portshield you can define additional WLAN Interface if the Device supports Portshield) .Then technically it might be possible to attach more than 2 SonicPoints, however we will not support more than then officially published numbers.