Well, there are legal rights and ethical or moral rights.
Noel and Mitch both signed on for little money when the Experience was formed. Their contracts guaranteed them a salary, and they signed them, so you could say “Well, that’s on them — they signed.” And legally you’d be right.
But no one at the time knew what a a big deal Hendrix would turn out to be, and that his legacy as a sure-fire seller would last — well, 55 years and counting.
And all of them were little more than kids when they signed — I don’t know if Noel and Mitch even had legal representation.
As the band exploded, a number of people appeared on the scene who figured out ways to make boatloads of money off Hendrix — the villains are well known — greed-heads taking money that they weren’t entitled to and which was never accounted for. No one knows how much.
With all that scramble for money, we can probably agree that the musicians involved were entitled to a share, despite what sort of contracts they signed as kids.
Others agreed, and there was eventually some kind of restitution made to Noel and Mitch in the years after Jimi died.
The contracts they signed to get that restitution would have been made when they were adults and had access to legal representation.
I don’t know enough to know whether their heirs (all three original members are dead) have any further claims now, legally or morally (that’s where my own cynicism kicks in).
The people who absconded with the most money are also dead. Are those people’s heirs living the life of Reily? No idea.
If you read any of the accounts of how the finances were handled at the time, there was a nest of vipers involved, and no way today, or even decades ago, to account for what went missing, or where it went.