Is it possible to add custom objects that have master-detail relationships with other objects that already contain records in Salesforce?
I've uploaded all of my data into the "Contact" object - this includes First Name, Last Name, Address, Total Dollar Amount of Purchases, and Total number of purchases.
The total dollar amount of purchases will be a "roll up" total of each purchase's dollar amount (in a separate "Purchases" object) associated with each individual in the "Contact" object.
The "total number of purchases" will be a "roll up" total of the number of times each individual in the "Contact" object purchased something.
There would be 3 records in the "Purchases" object associated with John Smith, and they are John Smith purchase 1 - $25, John Smith Purchase 2 - $50, John Smith Purchase 3 - $25.
The "Contact Object" would have John Smith - Purchases: 3, Total Dollar Amount of Purchases: $100.
My problem is that when I try to create the "Purchases" object AFTER already uploading all my "Contact" data, I can't make the master-detail relationships necessary for the "Total Number of Purchases" and "Total Purchase Amount" roll ups.
This is because Salesforce tells me that "You cannot create a new Master-Detail relationship on an existing custom object if records already exist. You must first create a Lookup relationship, populate the lookup field with data in all records, and then change the relationship type to Master-Detail."
I understand that the "easy fix" is just to make both objects from the start and THEN load all my data in after making the master-detail relationships.
However, this poses a problem if I wanted to add and track even more data in newer objects in the future.
For example, what if I decided I wanted to measure a new metric such as each record of an individual opening up a marketing email - with marketing emails in a new object to keep track of the dates, times, and even subject lines of each email?