Is there a way to include calendar invite or reminder on invitation sent

Yes

You can create  an ICS file in the web Portal. 

"An ICS file is a calendar file saved in a universal calendar format used by several email and calendar programs, including Microsoft Outlook, Google Calendar, and Apple Calendar. It allows users to share calendar information on the web and over email. For example, when users send a meeting request to others, they can share ICS files with them, who can import the meeting's details into their calendars."

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