https://beta.musicbrainz.org/series/50b1631c-df3b-4ceb-9adf-22381db6204f - the works were given numbers 1-5, but I hadn't entered a disambiguation comment. When submitting it the first time around, it warned me that another series already existed with the name, so I had to enter a disambiguation comment. I didn't notice that the "has part"-numbers had changed until I had clicked submit again.