I have something that I think is pertinent to add to a Resolved topic. Is there any way to do so ?

No. Once a question is resolved, there is no way to add anything to it. There would be no point as there's be little or no chance the asker would even go back to a resolved question to look for additional comments. Click on that person's avatar to see if they allow email. If so, you can email them. When emailing through Yahoo! Answers, all email addresses are kept anonymous at all times. At no time can anyone see your email address, nor can you see that of anyone who emails you.

Nope once resolved that's it.You can't add anything.