Exchange Rate Difference

If I check 'Local Currency Rate Diff' check box in OMRW:

1. If GR happens before IR, IR will be posted with the exchange rate of GR document.

2. If IR happens before GR, IR will take the exchange rate as of IR date. Then when tried to do GR, since (assuming there is an exchange rate difference between IR time and GR), giving an error because exchange rate on IR is different from GR and there is no place for the difference to go.

Please share if there is a way I can work around.

Thanks