Needs to set approval functionality in between of MRN and Invoice process

Hi,

I need some help but I am not sure about the problem means it will be resolved through functionally or technically. I am working as a Ax technical consultant and I clarify the whole scenario which is mentioned as:

4- users are involved in this process.

(i): A user has created a purchase order and posted.

(ii): 2nd user is responsible for MRN (Packing Slip).

(iii): 3rd user is from quality control means the items has been received and needs to check the quality of raw material. If quality parameters go to OK then the MRN will be needed to approve otherwise it will be rejected.

(iv): 4th user is responsible for invoice means he will do invoice for those MRNs which has been approved. no need to invoice for rejected MRNs.

In this whole scenario we needs to set approval functionality in between of MRN and Invoice process. I need speedy help.

Regards

Vimal