A direct rollover reported with code-G is required to be entirely deposited into qualified retirement accounts. If the plan withheld any amount for taxes or the plan distributed some to you in cash, that should have been reported on a separate Form 1099-R with code 1, 2 or 7 and you would need to contact the plan obtain a corrected code-G Form 1099-R and a Form 1099-R with code 1, 2 or 7 for the part not rolled over.
If you yourself inappropriately diverted some of the funds to cash or estimated taxes (not tax withholding), the Form 1099-R is no longer a valid reporting of the transaction. You would need to submit substitute Forms 1099-R, one with code G for the portion directly rolled over to the traditional IRAs and another with code 1, 2 or 7 for the portion not rolled over.
