The Witch Princess does not have any special requirements in this game. You marry her the same way you marry any of the bachelorettes. You must:
Upgrade your house twice
Buy the Wife's Bed
Have a Red Heart with her (her Heart Color is invisible though)
See all four of her Heart Events
Get a Sunstone from her
Raise Mystic Island
Give an offering to the Harvest Goddess (she lives on the pond on Mystic Island)
After that you can successfully propose to her using the Blue Feather.
Chat with our AI personalities
You can't marry her, but you can view heart events with her. http://fogu.com/hm8/villagers/alisa.php
You must want to marry Vaughn. Anyways you can't buy porridge. But here is the recipie, Milk (or Jersey Milk) + Rice (cooked) Hint! That's Vaughn's Favorite Food. And i know everything there is to know about Harvest Moon Sunshine Islands. I am a complet fanitic! If you need anymore help just e-mail me at linzy_king02@yahoo.com Your Welcome
If you have Vaughn on any hearts, you can still marry Will. But you cannot marry Will if yo have already married Vaughn
You can't marry the Goddess, but the girls you can marry are: Witch Princess ( her heart colour is invisible) , Julia, Natalie, Sabrina, Chelsea (the girl player that you can play in Harvest Moon DS: Island of Happiness) and Lanna, the popstar.
You cannot marry the Harvest Goddess in Harvest Moon: Back to Nature. Your options are Ann, Elli, Mary, Karen, and Popuri. You can marry the Harvest Goddess in Harvest Moon: Friends of Mineral Town.