I think this is possible to be implemented with not such a big effort.
You could define a new metafield for the Events module. Let's say, it will be the Subscribers metafield. It will have a longtext
type. You could store the subscribers like this:
Georgi Chokov<email@example.com>;Monika<firstname.lastname@example.org>;Someone Else<email@example.com>;
If you want to add someone to the subscribers, you could do it like this
|subscribers = EventItem.GetMetaData("Subscribers").ToString();
|string new = "new name<firstname.lastname@example.org>";
|subscribers += new; // or subscribers = String.Concat(subscribers, new))
When you need to know the number of the subscribers, in order to determine whether you are going to show the event subscription link or not, you could simply parse the string with String.Split method.
I hope this will help you. Just let me know if you need any further assistance.
the Telerik team
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