A message linked to the specific service user (rather than a message send individually to members of staff) that will pop up for a chosen number of days after opening their "profile"
I'm aware of the diary entrance possibility, but it doesn't quite cover the need as sometimes the notification is not time specified and it's not one explicit action that needs to be taken.
This would make the communication easier and remind the staff about non urgent but important issues (e.g.; "Mr X's father asked if Mr X can wear his Christmas jumper today, as they're planning to attend a Christmas party later.", "Please remember not to cut Miss's Y nails, as her sister wants to make an manicure appointment for them", "Please remember to monitor Ms Z reaction to new clothes and make sure it's not overstimulating", "Please remind Mr A to have his bag ready if he wants to join todays activity" etc. )