Automatic PO generation in VI01

Hi Experts,

I am having running scenario of Shiping Cost Transfer (VI01).

Here I am having settings in T_56 (Item Category) as below..

Generate PO - "A" Generate purchase order for validity period of 1 day

And it is running fine.

Now my client requirement is like.. They want system to create new PO on daily basis.. but if the Service Entry Sheet against one PO goes beyond 200 entries the system should generate new PO.

With the help of Item Category Settings its possible to make the validity of PO on the basis of Day, Week or Month.. But we need it on the basis of Number of Service Entry Sheet..

Any solution???

Thanks in advance..

Regards,

HP