Extension of stay for 2 year work permit

I have recently been given a 2 year extension of my work permit (as a director - Non BOI company)
 

For visa I have been doing yearly extensions of stay with the current reason being marriage, I am now considering to swap this to reason being employment (documents seem easier)

Does anyone know if I move to doing it based on employment will my extensions now be 2 years in length (to match work permit)?

Also for timing, my extension of stay based on marriage is still valid for ~6 months but if I swap to based on employment I would prefer to go change it now, will that be possible or need to wait till closer of the expiry of my current extension of stay?

Cheers