Yet, a traditional civil tamboon or familial ceremony is looked upon, within the culture/society, as perfectly proper and acceptable - sans the Amphoe or "legal" registration.
Know of numerous couples, throughout the years and decades, that didn't bother with the registration process and get on quite nicely without too many worries.
Mind you, this indifference to a legal marriage certification is probably become much lesser [almost nominal] in today's Thailand as the society has been forced to exist in a manner of overwhelming legalities........carefully borrowed from perceived civilised Western values. Kinda sad.