Some thoughts on typology, relative (and other) pronouns and Dairwueh, Bryatesle and Sargaĺk in light of Indo-European and Uralic
1. Typological preamble
the areas which Caesar conquered
at the time when she arrived
3. Specifics of relativization
Now, we can take the basic idea "formal conflation of so-and-so with relativizers as a stable feature in a language family". So-and-so doesn't even have to be pronouns - it could be some auxiliary, it could be some type of pronoun, it could be some conjunction. Relativization happens in many different ways in different languages, but I have decided to go for relative pronouns as one of the strategies present in all BDS languages.
4. Stable features in families
It's clear Indo-European does have some rather stable features over times: the three gender system (say I, writing in one of the languages that has lost it and speaking another that has reassembled it natively), verbal prefixes that are largely overlapping with prepositions, -a as a feminine marker (somewhat less stable), ... so, having a few stable features in Dairwueh-Bryatesle-Sargalk (as well as others in Cwarmin-Ŋʒädär) might very well lend these groups a more "family"-like type of grammatical style.
It is conceivable, however, that this is a type of survivor bias! Proto-Indo-European probably had quite a large amount of features. Just by random chance, we'd expect a handful of features to survive in multiple branches: us thinking of these features as resilient or somehow "characteristic" features of a family might be a mistake. They may very well be features that just have survived the elimination lottery.
4. Implications for Bryatesle-Dairwueh-Sargaĺk
So, as a kind of tribute to Indo-european, I will have a 'similar' correspondence as the one we just ... well, partially debunked or threw on the trashheap or whatever. After a way too long post, here's the nugget:
In BDS languages, relative and reflexive pronouns greatly overlap, and this goes back to proto-BDS.
I think this might require some reworking of Bryatesle, Dairwueh and Sargaĺk.