When asked if the HDC was now reviewing all Sherriff's reports used in past investigations, the office said: "This matter is under consideration".
Sherriff provided expert advice to HDC in 24 cases, some of which are open and some closed.
HDC said Sherriff was a health professional with extensive clinical expertise in the aged care sector, and was highly regarded in her field.
Robert Love called the situation "a serious problem".
"If you look at everything that spreads out beyond this, it's not just my complaint... it represents every single case that she's been used on for expert opinion and it's all got to be contaminated and it's all got to be looked at again."
Consumer NZ lead researcher Jessica Wilson said the conflict raised issues around transparency at the HDC.
"To request someone to do a review who is so involved in the industry and owns their own rest home is not a good choice."
The consumer watchdog last year called for an independent inquiry into rest home care after the Disputes Tribunal ordered Bupa to pay Love $10,000 for St Kilda Care Home's repeated failings in its care of 92-year-old Freda Love.
Wilson said for a process to give consumers confidence, no conflicts of interest should arise.
"We haven't seen the Commissioner's final report on this complaint but certainly their choice of this particular assessor does raise issues that consumers could question in terms of their independence and transparency across the process.
Robert Love complained about Sherriff's independence to the HDC in a letter last week.
He also pointed out that Sherriff, a registered nurse who has more than 25 years experience in the sector and co-owns a rest home in Christchurch, was employed by the professional association that promotes the interests of the residential care industry.
"Bupa New Zealand is by far the largest and arguably most influential client represented by the NZACA," he wrote.
"I do not wish to labour the point but Bupa is also the company I am complaining about."
Freda Love had suffered a stroke and could not talk or move her legs, and required an in-dwelling catheter which St Kilda Care Home staff assured her son they could manage when she moved there.
But Robert Love repeatedly found his mother in a urine-soaked bed after the catheter had been dislodged and on one occasion he found her freezing under a thin shawl in a wet bed with the window open.
He complained repeatedly to rest home staff and managers and to Waikato District Health Board, where Adams was previously the chief operating officer.
An unannounced audit by the DHB of St Kilda Care Home this year found many of the failings had not been rectified.
Love said Sherriff's report was biased but Health and Disability Commissioner Anthony Hill denied that and said the HDC placed high value on its independence and impartiality.
"We take any perception of conflict of interest in relation to our independent expert advisers extremely seriously.
"We have reviewed the advice in this case and we have seen no evidence of bias. Nonetheless, given some of the concerns raised we will be seeking new advice in this matter."
Sherriff said yesterday she could not comment on the situation.
Adams said she did not know Sherriff undertook work for the HDC and had never discussed with her, or any other NZACA board members, the Love case.
