I would add another release in the same release group with everything in one track.
The new release should have the release date as the date that it was put onto Soundcloud, and have the same artwork etc.
I think the track title would usually be each song seperated by a '/' eg:
Little Cat Steps / Chinchilla / Gravel / Mositif... etc
But that seems quite long and I couldn't find the style guide for this, so maybe someone else wants to chip in.
we would have:
Release name: BBC Radio 1 Essential Mix: Continuous Mix
Track name: BBC Radio 1 Essential Mix: Continuous Mix
And the track titles and respective artists are entered into the annotation.