adding open text box under parent/guardian details

I was thinking it would be helpful to have an open text box for secretary use only under the parent/guardian details tab, maybe on the right side in the open space?  I have had a few things come up- ie. mail is not going through to mom so I need to send it to grandma's address- that I would love to note there.  I currently have it noted under the evaluation details tab but it would be great if I could note it right next to the addresses.  Just a thought.  Thanks!