Sure, adding another field for NTP is pretty straightforward.
I haven’t had time to update the API document. The added option name is ‘dns1’:
the reason it’s called dns1 is that the ESP8266 library can accept 3 DNS servers, so in the firmware we left dns1 as user-configurable, and the other two default DNS server IPs. The format of this parameter is the same as other similar parameters (i.e. dvip and gwip).