delivery scheduling in PO w/o referencing PR

Hi Experts,

We are facing one control issue when PO made with reference to PR.

First check;

already built in that the said PO can not be made without referencing PR

Second check:

message 06 076 is error so PO qty can not exceed  than PR

But in delivery schedule tab of PO you can add n no.of lines and qty w/o referencing any PR.

No system message popping up.

So ultimately if PR is of 10 qty, then one delivery schedule line of 10 qty and with PR and line item no. will be there.

After that I can easily add another line in delivery schedule of 10 qty w/o referencing any PR.

So effectively my PO qty will become 20 and the message 06 076 will not appear for the 2nd delivery schedule line since no ref to PR.

Hence the control factor is loosing here,how the same can be aligned.

Regards