The practice handled about 600 family trusts, mainly formed by Mr Hughes.
"We have written to every one of those and advised them that they've been moved," Mr Ross said.
He decided last year he wanted a smaller practice, and the move happened on December 22.
"General practice is better done by a bigger firm," he said.
One of the purposes of the change was to improve Mr Ross' lifestyle. "I would never say court work is easy. It's just not. But it's the other responsibilities that you have running a general practice that we no longer have to worry about."
Stephen Ross did his legal training at Otago University, came to Wanganui for his first job and never left.
In 1992, he and Andrew Cameron left law firm Armstrong Barton. Four years later they set up offices in the top storey of Wairere House, also known as the Wanganui Computer Centre.
Until 2005 it housed a lot of justice sector information about New Zealand citizens. It had 150 employees in its heyday.
In 1982, Auckland punk rocker Neil Roberts blew himself up at the building, in protest against its perceived invasion of privacy.
The lower storeys are now one of three places where the country's film, newspaper and book archives are stored in climate controlled conditions by the National Library.
Mr Cameron was Wanganui's Crown Prosecutor for several years, resigning in 2008.
At its largest, Stephen Ross & Associates had 13 staff.
With the latest moves, Stephen Ross & Associates is stripped down to just three staff members. Mr Ross' colleague Raukawa Simon is soon to join him as a principal.