I am configuring a many-to-many relationship between custom object and Contact. For this purpose I created a junction object. Next, I have to create 2 Master-Detail relations. One for custom object, another for Contact. When creating a Master-Detail relationship field, my custom object is not visible among other objects. What could cause this problem?
There are a few rules that may help you. A custom object cannot be the master to a standard object. Master detail relationships can only be created where there are not existing records in the object on the detail side of the relationship. If this does not help you, it would help to have more information on what objects are masters and which objects are being used for detail. Thanks
I found the answer. Only two Master-Detail relationships are allowed per custom object. My custom object already had 2 Master-Detail relationships. I converted one field to lookup. After that, I was able to see this object among other objects when creating a Master-Detail relationship on junction object.
You can have up to three custom detail levels
i.e.., if childObj1 is already a great-grand child of another masterObj1, you could not be able set this childObj1 as master to another object. help.salesforce.com/… – sam_s Feb 1 '16 at 15:53