UHD 50p relink

Hi.

I successfully relinked HD 1080/50i to UHD25p. I successfully relinked HD 720/50p to UHD50p.

Now we shot on UHD 50p but edited in 1080/50i.

The rushes were transcoded in 1080/50i. The video is edited in 1080/50i.

We would like to keep a UHD master of the video.

But i'm not able to relink from 1080/50i rushes to original UHD/50p.

What can be a workaround?

Thanks