I have 3 objects Contact, mList and mEvent. mList is a junction object which has master-detail relationships to both Contact and mEvent. The mEvent has a picklist field called Group_Level__c (values 1,2,3,4) and Contact has text field called Member_Level__c.
My problem is that whenever I save/update a new mEvent record, I need the selected mEvent.Group_Level__c picklist value to be reflected to all Contact.Member_Level__c text values that are linked to it. (Contact.Member__Level__c values are dependent on mEvent.Group_Level__c value)
What is the best approach to achieve this? (An mEvent record can be linked to thousands of Contact records at a time and vice versa.)