Alert Rule Ax Customise for Usergroups instead of users

I am Stuck int trying to customise and create alert Rule for userGroups similar to the standard functionality of sending alerts to USER .

I added a User Group dropdown on the GUI which displays UserGroups , now i need to customise so as the alerts are send to the entire group similar to how it sends to a “User” selected currently.

Can you please help me find out which methods i need to update or edit so as to get my functionality working.

thanks and i would appreciate any help