No, seriously, why does this word exist? Not that it offends me, it just baffles my mind that we would have a word for this at all. Is there an equally imperious-sounding equivalent for aunts? Grandparents? Siblings? I have yet to find one.
“The avuncular politician bought pizza for the press.”
Avuncular – adj.
: of, relating to, or resembling an uncle
~per Merriam-Webster
The Coffee Writer 
I say if they don’t already exist we create are own. The following occurred to me:
Aunticular (or sticking closer to the inspiration, avauntular)
Grand-parental
Siblistic
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