nepotist


You're quite right, wsieb! Though according to Merriam-Webster, the word with unsavoury connotations is nepotistic so maybe we could invent nepotist as a neutral term for 'pertaining to nephews/nieces'?


the word is 'materteral' (no 'n')
Thanks tsuwm. Shame, as materternal sounds better. Sort of maternal plus something. Also has a hint of the eternal about it...