Here's an extender that allows you to use classic std 35mm cine lenses on Super 35 sensors.

Digitaloptik Image Circle Extender | Film and Digital Times (http://www.fdtimes.com/2013/05/10/digitaloptik-image-circle-extender/)

Could this extend 16mm coverage to super 16?

I suspect you'd need to test it, the image circle needs to be extended by a slightly larger factor for Super 16 than Super 35. However, because of differing image circles, it might be enough to extend some 16mm lenses to cover Super16.

They modified std 16mm zooms to cover Super16 by mounting a similar piece of optics to each lenses.

In another forum, some people have been asking if it would allow the use of Super16 lenses on the M 4/3 sensor BMC camera. Currently, there's no real answer to that, just that it might be possible, however, the question of having enough room for the rear elements of these lenses inside the extender was raised.