Is it possible for a person on a 60 day extension for visiting Thai family to apply for a non-O visa based on retirement while staying in Thailand after coming into country on VE and extended Amnesty?

I haven't applied for 60 day extension but just want to know if I do and its granted will I be able to then apply for a non-o visa based on retirement prior to its expiration.

No problem to apply for a 90 day non immigrant visa (category O) entry at immigration for retirement while on a 60 day extension to visit your wife or child. You must do the application before you have less that 15 days (21 at some offices) remaining on the extension.

OP, that's exactly what the 60 day extension can be used for. Obtain your non-o now.