Ability to change Subject of appointment booked on Portal through Patient file

Client wishes to be able to modify the Subject field of an appointment in patient file section (see attached) as currently it is greyed out. That same appointment; you can actually change the subject from the Calendar though

but from patient file much easier and convenient..

Mme Valérie SOULÉ
514-843-7904
valhorizons11@gmail.com
CLINIQUE MÉDICALE FÉMINA
Requête SF 226552