Disqualified trainer Lee Hope has unsuccessfully tried to join forces with Danny O'Brien and Mark Kavanagh as they appeal their bans for cobalt doping before a Victorian tribunal.

But while Hope was knocked back by the Victorian Civil and Administrative Tribunal, O'Brien and Kavanagh on Thursday had their stay of proceedings extended indefinitely.

This means the pair can continue to train until there is a final determination by VCAT on the lengthy bans they received for administering cobalt to horses.

VCAT president Justice Greg Garde dismissed Hope's bid to intervene in the O'Brien and Kavanagh case because he considered them separate matters, even if both centre on cobalt offences and penalties.

"No assistance is to be derived from mixing up the proceedings together," he said on Thursday.

Hope and his son Shannon were disqualified in November for three and five years respectively after they were found guilty of intentionally administering cobalt.

Soon afterwards, father and son were granted a stay of proceedings until their appeals against the bans could be heard before VCAT in February.

O'Brien and Kavanagh were granted a stay of proceedings by VCAT hours after they were disqualified for four and three years respectively by the Racing and Appeals Disciplinary Board on Wednesday.

The trainers and vet Tom Brennan were found guilty in December of the administration of cobalt for the purpose of affecting the performance of a horse in a race.

Four O'Brien-trained horses and the Kavanagh-trained Magicool returned levels of cobalt above the 200 micrograms per litre of urine threshold in 2014.

Brennan, who received a five-year ban, pleaded guilty to all but one of the five charges against him, while the trainers denied the allegations.

Unless there are special circumstances, the minimum penalty is a three-year disqualification.

O'Brien and Kavanagh want an opportunity to subpoena and cross-examine witnesses, including Racing Victoria stewards, at VCAT.

Their counsel, Damian Sheales, said they were not allowed to do this during the disciplinary board's seven-day hearing into the cobalt charges in December.

"During the entire brief hearing, no cross-examination," Sheales told VCAT.

The Hopes will return to VCAT on February 8, while O'Brien and Kavanagh have been given 21 days to gather further evidence for their case.