Joan Rivers

Joan Rivers

The Trumps have paid tribute to the late Joan Rivers.

Donald Jr. and Ivanka have revealed that Joan - who died in September 2014 after surgery complications - was the "most professional and the lowest maintenance" of all of those who made an appearance on the upcoming series of 'Celebrity Apprentice'.

The 33-year-old former model shared: "It was amazing to see her interact with everyone. It also showed a different side of [Joan]. She's very warm and very maternal and very protective of all of the contestants."

Her brother, Donald Trump Jr., 37, added: "From day one, [the crew] said that [Joan] was actually the most professional and the lowest maintenance.

"That's not the diva that she's known for, but she's always so generous and so kind to the crew, the sound guy, all the way up to the production team. That always struck me."

Joan - who replaces Ivanka as a judge in two of the show's upcoming episodes - was a "big part" of the judging panel when she appeared.

Donald Sr. explained: "[She] plays a big part in two of the episodes. She replaces Ivanka as a judge - and she was spectacular."

The family thinks Joan - who was 81-years-old when she died - will be "very happy" with the end result.

The 68-year-old businessman said: "We had a decision to make: 'Do we leave that in the show, or do we not leave it?' And we decided to absolutely leave it.

"She was so smart and so sharp and so good that she would be very happy. Looking down, she'll be very happy.

"We're doing a big 'In Memoriam' tribute at the beginning of the show."