I would do Jace for Jason. I think it has a clear pronunciation and it's a more natural cut off than Jay is.I think Cassy from family would be pretty normal, but I can also see a boy getting gruff about it.Lavinia- Nia, Via, Lia, Laney, Bonnie, Vin, Lin I like Annora "Nora" or "Nori" best.~Anna~