Grandpa and Grandma Longneck have one page and Ruby's parents have one page. However, Bron and Littlefoot's Mother and Mama Swimmer and Ducky and Spike's father and Topps and Tria have separate pages.
I think that, since they've pretty much always been together, and were always a couple (which is NOT the case for Topps and Tria), that they should have one page only.