If you have an ARC based on work permit and your spouse has a dependent ARC, can you convert both to a student ARC (assuming you get accepted to a school) without leaving Taiwan?
I found this thread which seems to indicate that you must leave Taiwan, apply for a student visa and then return.
However, the BOCA seems to indicate that you can convert from a visitor visa to a student visa
http://www.boca.gov.tw/ct.asp?xItem=6139&ctNode=778&mp=2
Though a work permit and dependent ARC are different from a student visa, I don’t see why you couldn’t do the same.