My sister is a supervisor and a salary employee at her job, she is also pregnant. She gets short term disability pay for 13 weeks after she has the baby. If she takes the short term pay but then quits right before she is due to go back to work, what

My sister is a supervisor and a salary employee at her job, she is also pregnant. She gets short term disability pay for 13 weeks after she has the baby. If she takes the short term pay but then quits right before she is due to go back to work, what are the consequences? Would she have to pay all that money back or is there nothing the company could do?