A change in plans regarding the person who will attend a school event
In this case, you want to tell the school about a change in plans regarding the person who will attend a school event. It would be appropriate to give the reason for the change, too.
Model
Conversational flow and useful expressions
Greeting
Regarding...
Reason
What you will do
Closing
Parent's name
Supplement
Preschools may have slightly different names – such as 「保護者参観」(hogosha sankan) or 「保育参観」(hoiku sankan) – for Parents' Day, a day when parents are invited to observe their children at preschool.