("their father").

Verbs whose stems end in -Vki, -Vpi, or -si optionally lose their -i before the plural marker:
: pastuki + tu -> pastuktu ("they sew")
: duhapi + tu -> duhaptu ("they pulled it off her head")
: dusi + tu -> dustu ("they grabbed")||k(i)|| -> x/___k occurs optionally across morpheme or word boundaries.
: ay + nk + kiduwe -> yak + kiduwe -> yaxkiduwe ("you untie me")
: