Database Design question
this needs a lot more information
they are going to have registry, church, and a LOT of other stuff  

you need to read a book on database design or do some tutorials as your design is not very good    

starts with weddings plural
they are not going go want a separate database for each wedding   

if everyone needs to logon then you need one table for that  

wedding:  
ID   PK
brideID   FK to user
groomID   FK to user
vendorID  FK to user


if you can have multiple vendors then need a separate table

user:
weddingID  PK  FK to weddingID
usrID      PK
password 
fname  (vendor just does not have fname) 
lastname 


if they are not brideID, groomID or vendorID then they are a guest