As a user I want to be able to send a notification to update or cancel the request for availability

[SSimong]

this is important for both AoT and Event requests but more important for events - i.e. an RCR gets called off and the members stood down.

[SSimong]

it should include the date/time and who sent it so it's clear how old the notification is and if it's a legitimate notification (as in someone who should be standing members down).