To display contents of lookup form with a subform

To display contents of lookup form with a subform

I have a Form A with a lookup field from Form B.  In Form B there is a subform C.     I want to display contents from Subform C when entering data in Form A, sometime with one entry in Form A corresponding to like 5 to 10 rows from Subform C. 

How can this be implemented?  I was looking for a field type like "Array" to display all records found in Subform, but the "on validate" action can't pull up Array values to populate such a field.