Complex sentence: Stefan was the son of Lazar and his wife Milica, who belonged to the lateral line of Nemanjić, since her father Prince Vratko was a direct descendant of Vukan, eldest son of Stefan Nemanja.
Split into simpler sentences: Stefan was the son of Lazar and his wife Milica, a lateral line of Nemanjić. Hrebeljanović's father Prince Vratko was a direct descendant of Vukan, eldest son of Stefan Nemanja.