Enabling Interpretation in a Webinar that's Already Scheduled

I have a series of webinars scheduled starting tomorrow morning with approx. 100 people per webinar. Each webinar will have local language interpretation. Unfortunately I didn't realise that I needed to set interpretation up when I scheduled the webinar. It seems that I can't set it up once the webinar has been scheduled. The problem is that I already have 100 registrants and can't schedule a new webinar. Is there any way to set up interpretation in a webinar retroactively?

Sorry, figured it out. It's possible when you click on "edit" for the webinar.