At our house it's simple. After the candlelight the boyfriend and his fraternity come over to our house. I know one time one of my sisters sat on his knee while he latched the lavaliere to her while his brothers sang their sweetheart song to the couple.
I think you can approach it however you want. I say go for theatricality if you can!
Congrats! I wish my boyfriend was in a fraternity so I could get lavaliered!!!