Is possible to validate all Requisitions lines to be "Purchase Requisition" or "Internal Requisition

We have some differents Approval Rules depends of the document type: if it is a Purchase Requisition will have more restrictions to be approved (Hierarchical approvement) but if it's an Internal Requisition the Req will be approved by the Requester.

But the problem is when I mix in the same Requisition, lines with different sources: Supplier and Internal. All requisitions lines goes to the "Hierarchical Approvement" process, and as I told you, they should have different approval rules.

Is there a way to avoid this behavior? I would like to split the requisitions into: Supplier or Internal lines or not let the user create mix-requisitions.