This is despite consultation documents claiming they have been.
Representatives of the Children's Heartbeat Trust said they were "dismayed" after it was made clear to them that local medical bodies did not endorse, consider or envisage the application of the Safe and Sustainable guidelines on an NI basis.
Speaking at a picket outside a meeting of the consultation working group on Friday, they told UTV that Stormont needs to act to save the service.
William White, whose granddaughter was treated at the Children's Hospital, said: "I think it undermines the whole premise that this consultation process was set up for.
"I mean, they told us at the very beginning that the guidelines under which they were operating in England and Wales were the same as here, that these guidelines had been endorsed by the medical bodies in England and Wales.
"It's not true yet this whole process has been set up under the premise that these guidelines have been followed."
Concerns about the future of paediatric cardiac surgery at the Royal were first raised back in August last year, when Health Minister Edwin Poots confirmed that the service was under consideration.
A review had found that although the unit at the Royal - which sees around 90 operations carried out annually - was above par, it would not be realistic to maintain.
If the provision of paediatric congenital cardiac surgery is withdrawn, young patients across Northern Ireland may have to travel to England for treatment.
Hundreds of people marched to Belfast city centre from the Royal Belfast Hospital for Sick Children last weekend, in a rally against paediatric cardic services being cut.