RE: Can we create a lookup for the particular column in the case entity ?
Hi Prashant.ITT,
Custom entity(child) and case(parent) is N:1 relationship,The 'customer id' is one lookup column for case in the custom entity?
" it should be automatically associated with the case number and whenever a case is created the applicant id will be the same as the case number."
So you want to create custom records automatically when you create one case, and the 'customer id' should be filled with case number?
You can use workflow to create child records when you create a parent record.
OOB workflow can't create child records, you need use 'Update Child Records' of Dynamics-365-Workflow-Tools
But lookup field displays the case title instead of the case number by default.
So you can create a new field to store case number or use quick view form to show it based on the lookup field.