Why can't a Salesforce Junction Object be on the master side of another master-detail relationship?

Hi Rahul,

First we need to know why we create junction object---

We create junction object to get many to many relationship functionality, a many to many relationship allows each record of one object to be linked with many records of another object or vice versa.

Salesforce allows only two master detail relationship on any object, as junction object has two masters so when we make master detail field on another object, the name of that junction object will not be shown in the 'Related To' picklist.

Hope this helps.