I don’t personally see any issue with this split, since here is a distinct change in the members and name at the same time. could also use this new relationship to connect the two~
https://musicbrainz.org/artist/e5257dc5-1edd-4fca-b7e6-1158e00522c8
looking at their artist page, there are several URLs for both The Jackson 5 and The Jacksons, and they’re also separate in several other databases, including Allmusic, Discord, and RateYourMusic
edit: while browsing their artist credits, I just found this release that also specifies it’s both The Jacksons and The Jackson 5 (this does seem to be the only case they’re both credited on a release tho)
https://musicbrainz.org/release/228a7f4b-388f-4a29-88ee-3432da5c9a04