What are the legal requirements for Forms TM30 and TM28 for expats in Thailand?

Rather than descriptions of what various immigration offices may or may not require, I am interested in an interpretation of what Thai Immigration law actually says about Forms TM30 and TM28. For example: If I enter the country, stay at a hotel in BKK for a few nights (presumably they fill out a TM30) and then travel up country to live in my wife's house, am I required to fill out a TM28 as notice of staying in a new province for over 24 hours? If I go to Cambodia to begin a new 90 day entry on my Non-O multi, is my wife legally required to fill out a new TM30 to match my new entry card? I know different offices handle these things differently and if I have no more to do with immigration they may never find out. BUT, I am interested in what the law actually requires.