Hi Bbdoll, I love throwing huge formal weddings. I use lots of cheats when I do.Â
1)
Guests- Go to your phone and create A New Sims Group. I just name mine
 "Wedding Guests". Make sure all of your relationships are way up there in the relationships with the guest/family. To make sure that they show up to the wedding check their work schedule's and make sure they have that day off. I usually just make them all unemployed so there is no excuse; like a sudden promotion orÂ
something.
Go into each family lot that you have chosen in your sim group and make sure hair, make up and clothing is all picked out for Formal Ware. Just leave them in Formal ware if you want.
Next:  Take your group on a test drive or two. Call Group  (Wedding Guests) and go for a outing just for fun. Go to dinner (make sure you have a restaurant with a big enough table for your party.) By calling your group and going to dinner they will all sit at the same table. I just have my main sim order Chef's special, that way everyone gets what they want. This is a great time to practice giving a
Toast  and practice some interactions at the table between future bride and groom. Next do another
Call Groups for a outing. Have a nice successful one. Use cheat codes to make all in your group become friends at the dinner table it is easier that way for me and it makes the score go up higher on your outing just like on a date.
2) Have a dresser and mirror handy and close by at your house or church just in case one of your sims forgets it is a Formal occasion. If this happens use bool prop to  make them playable long enough to get them to change and bring up any social or motive needs. hee hee.
3) Use your phone to Call Groups. Invite "Wedding Guests" for outing
just for fun.
 4) Use phone and Throw Party, Wedding Party. Invite only people that are not already in the Wedding Group. When these guest arrive, go to each of them and invite them to "Join Group". When you have them all, make the sim who has invited everybodyÂ
"Walk to Lot"  choose your church and soon everybody will follow you to the lot. As soon as you get there click on your wedding arch. The Bride and Groom will take their places but you will have to improvise with the priest. Just have him on the guest list or the Wedding list. But the Bride and Groom will wait for most of your guests to be seated. If I wanted two particular sims to sit in a certain place I just make them sit there. Dont forget to release them after the ceremony.
Hope to see some great pictures,
Happy simming.