Split FI document if more than 999 GRs

Hi,

We need to identify user exit/coding when creating an FI document at Invoice/ Credit Memo posting .

This code should split out the FI document and assign a different doc number if the 999 line item limit is exceeded (if

we have more than 999 GRs) .

Kindly guide how to acheive this.

Thanks & Regards,

Harshada