Změňte omezení cizího klíče v tabulce Grant.
Viz http://www.sqlfiddle.com/#!2/04945
CONSTRAINT `InstrumentGrant`
FOREIGN KEY (`RecipientID`)
REFERENCES `Entities` (`ID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `InstrumentGrant_2`
FOREIGN KEY (`DonorID`)
REFERENCES `Entities` (`ID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION
Pojmenujte omezení, jak chcete.