John Stirland, 55, and his 53-year-old wife, Joan, were found dead at their home in Trusthorpe, Lincolnshire, last summer.
Five of the eight defendants denied a joint charge of conspiring to murder the husband and wife between 1 and 9 August last year when they appeared at Birmingham Crown Court.
Three of these five, aged 28, 38 and 39, cannot be named for legal reasons. The two who can be identified were Shane Bird, 37, of Carlton Hill, Nottingham, and Michael McNee, 20.
Although a previous restriction banning the identification of Mr McNee was lifted by the judge, Mr Justice David Clarke, an order was put in place stopping the publication of his address.
The three remaining defendants - Lanelle Douglas, 19, of no fixed address; Andrew McKinnon, 21, of Gunthorpe Close, Nottingham; and Kevin Holm, 37, of Cliff Road, also Nottingham - did not enter pleas. They were expected to be arraigned at a hearing on 16 September.
Mr and Mrs Stirland, a former factory worker and nurse, moved to Trusthorpe last year, after Mrs Stirland's son, Michael O'Brien, was charged with murder. Michael O'Brien was convicted, and given a life sentence for the murder of a 22-year old shopfitter, Marvyn Bradshaw.
Soon after the killing, Mr and Mrs Stirland fled their Nottingham home after shots were fired into their living room. On the day they died, Mrs Stirland called the police about a prowler seen near their bungalow. When an officer arrived seven hours later, he found two bodies.
A trial was set for Birmingham Crown Court on 6 March next year. All eight defendants, who appeared via video link from prison, were remanded in custody.