So I have been trying to create a trigger to create follow up Tasks automatically, when a given Task is completed with somes dependencies to Contacts and Account fields, and with substantial help from this forum I have been able to do so. Here is the code:

Trigger FollowUpTask on Task(after update) {

     Set<Id> completedTasks = new Set<Id>();
     Set<Id> contactIds = new Set<Id>();
     Set<Id> accountIds = new Set<Id>();
 
     for (Task task: Trigger.new) {
     
          if (task.Status != Trigger.oldMap.get (task.Id).Status && task.Status=='Completed')
               completedTasks.add(task.Id);
               contactIds.add(task.WhoId);
               accountIds.add(task.WhatId);
          }
 
     contactIds.remove(null);
     accountIds.remove(null);
 
     Map<Id, Contact> contactMap = new Map<Id, Contact>();
     Map<Id, Account> accountMap = new Map<Id, Account>();
 
     if (!contactIds.isEmpty()) {
          contactMap = new Map<Id, Contact>([
               select Contact_Frequency__c,
                    Name
               from Contact
               where Id in :contactIds
          ]);
     }
 
     if (!accountIds.isEmpty()) {
          accountMap = new Map<Id, Account>([
               select Primary_Contact__c,
                    Name,
                    Tier__c
               from Account
               where Id in :accountIds
          ]);
     }

     List<Task> newTasks = new List<Task>();
     for (Id id: completedTasks) {
          Task task = Trigger.newMap.get(id);
          Contact contact = contactMap.get(task.WhoId);
          Account account = accountMap.get(task.WhatId);
 
          if (account == null || contact == null) {
               continue;
          }
 
          Task newTask = new Task(
               Subject = 'Follow Up ' + account.Name + '/' + contact.Name,
               OwnerId = task.OwnerId,
               WhoId = account.Primary_Contact__c,
               WhatId = account.Id,
               Priority = (account.Tier__c == 'Tier 1') ? 'High' : 'Normal'
               );    
 
          Date duedate = system.today().addDays((Integer)(contact.Contact_Frequency__c));
          newTask.ActivityDate = dueDate;
 
          newTasks.add(newTask);
     }
 
     if (!newTasks.isEmpty()) {
          insert newTasks;
     }
}

But now I was wondering if something similar is possible for Events, with multiple related contacts. The objective would be: when an event (with several contacts) was completed, the trigger would create individual followup tasks for each individual contact in a similar way the code above did. Is it possible to adapt the code above (an event trigger) to satisfy this requirement? I guess the modification would be to check each WhoID's parent account for the WhatID of the new task, as opposed to using the task's WhatID.

All help is appreciated