Scheduling and managing events using Outlook.com calendar
If I understood correctly, when you "reply to the invite" sent to your manager, you are then able to add attachments or copy and paste information in. But, I have not tried it. This is what I thought I read in one of the comments from Microsoft.
But, this is a problem if you "accept" the invite, but then LATER have to go back in and update or attach some documents or comments.....why they did this makes no sense.....