I sent in the paperwork for my license renewal a few months ago and even though no "change of address" form was included, and I haven't moved in the last six years, they still registered a change of address. I don't know why - normally people don't have trouble with my handwriting and anyway, how hard is it to distinguish a 0 from a 1?
Fortunately they only changed that single digit in the house number so my renewed license ended up with my neighbours across the street. I sent them a stern e-mail and two weeks later got the corrected license back at the proper address.
So this suggests that you don't have to use the official form. Any form of communication will do.