Which, let's be clear, never existed. No Lurian extant today has ever held any land in D'Hara, nor are any descended from or related to anyone who held land in D'Hara, and the "original" claim is basically a fiction as well.
It's a neat fiction that I am glad ya'll came up with because it adds some real spice to the game.
But ya'll have as much claim to D'Hara as the Moot has to Candiels: it'd be a sweet addition to our territory and we can confabulate some reasons why it Kinda Makes Sense for us to get it, and we can even dig up a quasi-legal piece of paper here or there. But it's basically just a baseless assetrion we're making.
Luria's claim *
at it's worst* is AT LEAST equal to D'Hara's claim to the D'Haran isles. Luria's claim is based upon having been the first realm to send a colony expedition to the lands currently held by D'hara. This was an official colony of Luria. The colony failed, but it established a claim to the lands.
Other land claims come from Luria's negotiated split of land claims with Morek as two of the founding realms of Dwilight. The only lands that Luria no longer claims from those treaties are the ones they have formally given up in treaties through other negotiations since then.
If D'Hara's greatest claim to the D'haran isles is that they colonized them, then they can't claim any greater right to it than Luria. Especially because it came after Luria laid claim to it.
The simple fact of the matter is that Luria was one of the founding lands of Dwilight and through such was able to lay claim to many more lands than it controlled or was even remotely able to control at the time. Those claims have been reduced over time closer to what they can physically control, but original claims don't just disappear. D'Hara wasn't a founding realm of Dwilight. So, while Luria's claims have descended from Monarch to Monarch through the Lurian Empire, D'Hara can't claim the same.