How to add Custom Document Type in Requisition (Purchasing)

Hello,

In Purchase Requisition form I need Type "Internal Requisition for Business" along with seeded dropdowns i.e Internal requisition and purchase requisition.

Actually based on this type Internal Sales Order will be created and it will have different approval hierachy for  Internal Requisition for Business Document Type.

How to achive it?

Do I need to create a custom form same as Purchase Requisition or i can create a New Document Type in Purchase Requisition?Need help on this.

There exists Internal Requisition defined as:

Can i create a new document type same as Internal Requisition and named as "Internal Requisition for Business" and defined the Approval setup same as above?