The parents behind the centre of a heart transplant drama said Thursday they were thankful for a “happy ending” after their frail baby girl finally received a new heart, while acknowledging the moment was bittersweet because another child died so theirs could live.

The parents of three-and-a-half-month-old Lillian O’Connor held hands tightly and wept as they said they’re relieved their daughter is OK, but admitted it was difficult knowing what another family went through so she could have a chance to be healthy.

“It’s hard to be up here and celebrate when we know that there’s another family that’s mourning at this moment, but we just want to thank them very much for their gift and their strength,” said father Kevin O’Connor, who frequently paused to compose himself during a news conference at the Hospital for Sick Children.

He said the generosity of the donor family was overwhelming, calling it a gift his family could “never repay.”

He also thanked all the other families he had met at the hospital.

“We’ve shared rooms with people we’ve come to care about and we’ve watched their children go home with them, and unfortunately we’ve watched some of them pass away,” O’Connor said.

“They will forever be in our hearts and in our minds.”

Lillian, from Prince Edward Island, had been waiting for a heart since she was born. Her parents, O’Connor and Melanie Bernard, said their daughter is recovering well at the Hospital for Sick Children.

The hospital is where Lillian’s parents first met the mother and father of baby Kaylee Vitelli, who suffers from a rare malformation of the brain.

In April, Kaylee’s parents offered their daughter’s heart, if she died, to Lillian.

The story created controversy for weeks as Kaylee’s father Jason Wallace held daily media briefings outside the hospital.

But Kaylee recovered and a transplant was no longer an option, so she was taken home to Bradford, Ont., on May 14.