PO line with prepayment invoice matched to it, is allowed to be cancelled

Hi,

In a Complex Purchase Order,  advance amount and recoupment rate is mentioned on Line 1.  Prepayment Invoice is entered and matched to Line 1 in Payables.  Prepayment invoice is paid.

Now the application allows cancellation of Line 1 and hence the user wants to cancel it.  If Line 1 is cancelled, the Prepayment cannot be liquidated / applied against any invoice.  As per the standard functionality, prepayment gets automatically applied, when a standard invoice is matched against the same line as the one on which advance was entered.  But here, if the line itself is cancelled, there is no question further billing against this line.