Does Sigma Kappa have a mothers pin ceremony at all? Or do you just want to make up your own? Check on this first to make sure you're complying in regards to ritual, etc.
If not then I see no harm in making up a simple ceremony. Use songs that you might use during pref night and have each sister say a few words to the parent they are honoring. They can thank then for their support of their membership in Sigma Kappa.
Just an idea to get you started..................
