I want to add relationships to link recordings of UNDEAD CORPORATION to Touhou songs.
Should I make arrangements for those songs, or add them as cover recordings?
Also, a song by them - Can’t Sleep Because It’s Nighttime has 2 different versions with different vocalists:
Another thing is that on one of their releases, there is a lyricist mentioned.
Both facts make me lean over to arrangements.
Not sure I understand enough of the specific context, but:
Touhou tracks iirc don’t have vocals, so any cover that incorporates them would be a separate work since it would have a lyricist credited to it.
I don’t know if those 2 tracks I mentioned have different lyrics, but since they have different vocalists, I think they would be 2 recordings of a work that is a arrangement of original Touhou work.
I don’t know about songs’ impact. For now, I care about if they have different versions of their recordings.
For another example, in this release there are 4 versions of a track 両目ひらけば桔梗咲く.
I think that would make for a work called 両目ひらけば桔梗咲く that has those 4 recordings attributed to it.
In such case I would want to treat their every track as a work.
technically, most covers would be arrangements in general (at least in a musical sense), but as said above, unless there’s several recordings of the same arrangement, new or translated lyrics, or some inter-work relationship, usually they’re just entered as covers
(I will admit, I added that last one)
also, I’ll see if @Silver_Skree can help, as they’ve put in a lot of work (heh) into Touhou arrangements
Arrangement works are usually more for classical.
Here it is even the same style, but even if the cover was reggae style instead of metal, I would just link as cover.
Difficult to understand the lyrics.
It’s a new work of lyrics are different.
In short, I say yes to arrangement, no to covers, wherever possible, for Touhou music (and vgm overall). It’s not always necessary (especially for relationships where lyricists aren’t involved), and often isn’t followed, but here’s what I personally do when I’m in your shoes:
As for the vocalist, add that as a “vocals” performance relationship to the recording, and other performers (for things like instruments, whenever they’re listed) get the same treatment.
If you have two versions of the same arrangement, I’d say link both Recordings to the same Work, but obviously the Recordings with different performning vocalists would have different Vocals relationships.
You can see this Work by Silver Forest and its linked source and recordings, for an (old) example of how I arranged something in a similar state to what you’re describing: Song “霞舞う月の丘に” - MusicBrainz
There’s kind of a line separating the “concrete” and the “abstract” on MBz, with Recordings and Releases being on the concrete side of this line, and Works occupying the abstract side.
MBz has the Releases and such for the various Touhou soundtracks, but linked to all the Recordings on those Releases, are Works for each track. Those Works are organized into parent Works for the game they’re from, and those parent Works representing the game are collected into a Series right here: 東方Project - MusicBrainz
This is a way of cataloging video game music on MBz that I’m massively fond of, and I like to give soundtracks this same sort of makeover whenever I’m working on them… but this is getting off on a tangent 
Point is, you can use that page to hopefully find whatever Work for the source tune you need in order to establish the link to the arrangement.
Best of luck and happy editing!
I’ve added ~500 touhou releases like this:
Linking Source materials:
- “cover of” or a new work (“arrangement of”/“based on”/etc.)?
Cover unless separate work entities are “needed”.
Explanation:
From the Work-Work / Other Version page:
This relationship should only be used when separate works are needed (e.g. when there are significant changes to the lyrics or music). In most cases, new versions of a work should simply be performances of the original work.
Basically this:
- “arrangement of” or “based on”?
Honestly, I’m not sure about this, but generally, when a new composer is credited, I go with “Based on”. An example
Explanation:
From the Arrangement relation page:
Note: This should rarely be used for pop music, where you should generally just link both recordings as performances of the same work, with the “cover” attribute checked if appropriate.
From the Based on relation page:
The new work must be a new composition, not just an arrangement or the same music with different or translated lyrics
I’d also like to mention that I’ve added a section about this on the wiki – anyone feel free to expand on it.
Linking arrangers:
Explanation:
From the Relationships Style Guideline:
You should always prefer the most specific level that you can
From the Artist-Work Arranger relation page
This relationship shouldn’t generally be used for popular music. Use the recording level relationship instead.
Track artists:
If an official source (CD sleeves, discography page) provides track artist credits, I use that.
If not, I fall back to the release artist, as per Wiki.
If anyone thinks I got something wrong or missed a guideline, please notify me b/c nowadays I’m cleaning up my old edits 
I believe arrangers should be credited on arrangement works, but besides that, they go on the recording level, correct
Thanks for all the feedback. If there will be a lyricist or arranger mentioned, I will make works. When there will be little to no information, I will treat a track as a cover.
If new lyrics, yes, new work.
But if only new arrangements, not new work, but recording-artist arrange relationship, and work-recording cover relationship of existing work.
As already mentioned above, that is not correct.
This relationship shouldn’t generally be used for popular music. Use the recording level relationship instead.
Touhou is popular music, not classical music, as far as Style is concerned.
Would that still mean there should be made new works for the tracks, with arranger relationship just moved to the recordings?
that’s a general rule, not a universal rule. there are cases in popular music where an arrangement work should be used (tho not common), and this is one of them, in my opinion
If several artist perform the arrangement, could be.
But no need arrangement work, if it’s only for 1 recording, IMO.
Before reading new responses, I made some edits to the release I mentioned at the beginning.
When we will reach a conclusion to this, I will edit that release again if I will need to.
Now, I think my approach would be like this:
On a cover recording, I would set the arranger relationship on the recording.
But for a arrangement work that has multiple recordings, it feels redundant to add arranger relationship to each recording.
In such case, would arranger relationship on a work still be a issue?
I think it’s usually the case that even if an “arrangement work” has multiple recordings, the “original” arranger wouldn’t be credited as the arranger of the additional recording. That makes it factually incorrect to put the arranger on the work, which makes Picard and all other clients of the MusicBrainz webservice pull in an additional, factually incorrect arranger.
So, as already mentioned, “This relationship shouldn’t generally be used for popular music. Use the recording level relationship instead.”
If arranger relationship must be always on a recording no matter what, then new lyrics with lyricist credited, and/or multiple recordings would be the only conditions for making a work.
Then I would need to move arranger relationship from the works to the recordings on the release I already edited.
Most of tracks there have lyrics, so I would leave them as works.
With that correction, would there be any more issues?
When there are several different recordings that use the same arrangement, then I think you can use a new work with arrange credits on it, not on recordings.
However, again, you’re only supposed to create a new work if there’s “significant” changes to the lyrics or music (different instrumentation in non-classical music is not considered a significant change in MusicBrainz). So in most non-classical music described as “arrangements”, this subjective threshold is rarely met.
Using the subject currently under discussion (Touhou), Song “ナイト・オブ・ナイツ” - MusicBrainz is one of the most well known “arrangements” which has dozens of recordings not currently linked. These recordings neither all deserve separate MB Works, nor should they all use the same arranger credit. (Furthermore, as noted in MusicBrainz Terminology, many of these “remixes” are not in fact remixes but are arrangements/covers.) So, I have to repeat, a third time,
This relationship shouldn’t generally be used for popular music. Use the recording level relationship instead.
Most of UNDEAD CORPORATION’s songs have vocals while Touhou tracks don’t, so that is (I think) a significant change, although I wouldn’t use other version relationship. I would just use arrangement.
So I don’t see a problem in adding new works.
Then only lyricist would be a relationship on a work, and everything else (including arranger) would go as relationships on the recordings.
As for multiple recordings, here are cases of recordings having the same names (those could probably be merged), and some recordings having different names (multiple versions of Magus Night Fever, MEGALOMANIA etc.).
I would just add them to the arrangement work.