The split gift box would only be present on previously saved gifts if:
The gift has not been Exported to GL
The gift does not have a soft credit
The gift does not have a matching pledge
The tender payment method (credit card/EFT) has not been processed * **
* When a gift’s tender uses Real Time Processing the transaction is created immediately upon save; therefore the split gift option is only available prior to saving the gift.
** When the process method is set to batch (to be processed later via Bank/Credit processing) the split gift box option will be present prior to running the Bank/Credit Processing.