I've been unable to find anything that definitively says you both need to file the Section 216 return. As long as you are reporting the full amount on your husband's return and not splitting it 50/50, it should not pose a problem. Changing it now after this many years may cause CRA to question it as their computers tend to be programmed to detect changes in reporting.
The following link contains some great information and FAQs about Non-Resident property owners. 🙂
http://www.rlg.ca/non-resident-owner-information/