can you not just assign your task to multiple people?

My requirement is to design a reminder list, where users fill the fields (Reminder date, number of reminders, interval between reminders, send to, Cc ... etc). then the WF run on the reminder date and use the reminder feature in the action. and reminder will stop when users choose to stop it.

I've used one flexi with one branch to achieve this. but users requested to receive one email including all recipient to ease the follow up.  

is there any other idea to achieve this?