Llŷr
The Welsh Triads states that Llŷr was imprisoned by Euroswydd , and presumably , Penarddun consequently married Euroswydd , giving birth by Euroswydd to her two younger sons , Nisien and Efnisien , as stated in the Second Branch . 
<triplet> Euroswydd <subj> Nisien <obj> child <subj> Efnisien <obj> child