Custom additions to meeting invites.

Hi All.

I have had a customer request that i thought would be worth investigating.

The ask was to have a custom addition to a meeting invite that identifies if the meeting is, for example, a personal meeting or business meeting..   This can simply be a radio button in the invitation that then highlights this to the attendees and in the calendar.. 

This is so that the customer can force users to input their business meetings via their CRM tool.  What they would like is for a dialogue box to be displayed if selecting anything other than personal meeting indicating that the meeting should be set up in their CRM. 

Is this at all possible or has anyone come across anything similar to this. 

Thanks

B