The certificates can be purchased from the Marketplace for 2500 sc's which come in a pack.
Light Wedding Chapel Pack
This Wedding pack includes two wedding rings, a wedding cake and a certificate that can be given to Anibarean of the Light to open up your own personal zone for a wedding. this zone is white and bright.
Dark Wedding Chapel Pack
This Wedding pack includes two wedding rings, a wedding cake and a certificate that can be given to Anibarean of the Dark to open up your own personal zone for a wedding. this zone is accented in black.
no idea if you can obtain them from anywhere else