Converting meeting to webinar but meeting is recurring

I have a recurring meeting set up but this month I want it to be a webinar. It seems that you can't convert a recurring meeting into a webinar (option doesn't even show up). The meeting link is already published so I can't create it as a new webinar - unless there is a way to override the webinar link with the original meeting link. Any ides on how to work around this? I also tried duplicating the meeting as a stand alone so I could covert that but that changed the link and meeting id.