Question: Who is Domnall Mac Muirecáin's sibling-in-law?
Sentence (from "Cerball mac Muirecáin"): He fought alongside Flann (whose daughter Gormflaith ingen Flann Sinna he married), against the men of Munster at the Battle of Bellaghmoon (near Castledermot) where Cormac mac Cuilennáin, King of Munster and Bishop of Cashel, was killed.
Relevant evidence: Yes