I think the suggestion is to first submit the release with just one medium and then immediately edit it to add the other media because indeed, I don’t think there’s a way to both create new recordings from the release editor and also link them to multiple newly-added tracks.
(You could also create the recordings first but that’s super tedious. Merging recordings afterwards is also an option).
Yes, create the release from Disc ID for the CD layer easily.
Then edit the release to add medium from existing medium (CD layer). 
We’re running in crcles here… since I don’t submit DiscIDs I’ll just create new releases as best as I can. Since I also learn from example, let me just cite 3 biggest problems with MB releases - a personal opinion which says “Do what little you want” and continue editing with my own priorities
He he, just a last try, because I didn’t understand why you don’t submit DiscID:
Adding release through DiscID is not something more too so, it is a way that makes the task so very much easier and quicker. 
https://musicbrainz.org/report/CDTOCDubiousLength
The new report is available, thanks @yvanzo and @reosarevok
https://musicbrainz.org/report/CDTOCDubiousLength
All the listed Disc IDs and their related releases have already been checked, most of them have pending removal edits now. Only a few results have not been removed because their times are likely correct, yet they were artificially created (multiple CDs entered as one, Disc ID for a DVD).
Thanks to @chaban and a few other quick editors for their help to finish this report within a day of its release
Some releases still need their track times to be corrected manually after the removal edits have been applied because the wrong Disc IDs were used to set them.