When a web-service call is made using inc=work-rels, rather than only include the immediate parent of the current work, instead include the entire ancestry of part-of works. So for example ...

At present a call like https://musicbrainz.org/ws/2/work/7500be55-0a9d-4385-bc25-5343764d8961?inc=work-rels for Die Walküre: Act I, Scene I. "Einen Unseligen labtest du" includes only the immediate parent work 53016124-b4a6-4fe9-bf08-b9a5289a7dc1 for Die Walküre: Act I, Scene I.

After this ticket is resolved it would include the following ancestors:

53016124-b4a6-4fe9-bf08-b9a5289a7dc1 Die Walküre: Act I, Scene I which is part of
c3869a71-dcd4-4ed2-94d7-3e92420b2ec7 Die Walküre: Act I which is part of
a87e8996-da9e-49a8-80f2-c5d8342b67e6 Die Walküre, WWV 86B which is part of
597e017a-2c97-40c0-9eeb-430a0461e4ad Der Ring des Nibelungen, WWV 86

This would enable tools like Picard to e.g. tag music with more comprehensive metadata.

It would not, however, include siblings of any of the above works like Act 1 Scene 2, or WWV 86A.