Sarah Keene, partner at Russell McVeagh and acting for Fairfax NZ, said any large buy-up of shares by an overseas company would need to go through the Overseas Investment Office (OIO) approval process.
Another possibility was using a deed poll process to make it compulsory for a merged entity to remain a member and founder of the Press Council. Members of that voluntary council sign up to charter commitments including that owners don't exert influence over editorial decisions.
Greg Hywood, editor and group chief executive of Fairfax Media, the Australian company that owns Fairfax NZ, said a stronger entity - as would be created under the merger - would be less susceptible to takeover.
Earlier, Hywood told the commission that editorial independence "is absolutely at the core of what we do".
Hywood cited the case of billionaire and mining magnate Gina Rinehart, who became a large shareholder in the company but would not sign up to a charter that protected editorial independence.
She was therefore passed over for a position on the board, Hywood said: "it's something we take very seriously".
The Commission's draft determination found the merger would threaten the range of voices, opinions and issues that the news media might cover, therefore producing an outcome not in the public interest.
Asked about diversity within the companies, Shayne Currie, managing editor of NZME, said there was diversity in opinion pieces, with more than 20 currently online about Prime Minister John Key's resignation.
Those included one by Rachel Stewart, titled "John Key era one giant face palm" which was "completely opposed to a view that Mike Hosking has written", Currie said to laughter from the room.
Academic and former Herald editor Gavin Ellis, joining by teleconference, said there was a danger that a merged entity would lead to decisions being made by fewer people, but affecting more publications.
Brian Fallow, former Herald economics editor and who still writes a column for the publication, told the commission he had seen cuts to journalism roles in his career.
"If you are concerned about competition, there have to be journalists to be competing with each other...the question I think for the Commission is, does that stanch this hemorrhaging loss of journalists and stabilise it...or is it simply an opportunity for further job losses?
"Because when I hear 'duplication' and 'replication', that sounds to me like code for synergy and the opportunity for still more reduction in the number of journalists.
In response, Simon Tong, Fairfax NZ's managing director, said its submission to the Commission and work by PwC had identified the number of journalist roles identified as synergies is "modest".
"And effectively it is an Auckland story, because there are two Auckland newsrooms. Really, the majority of the synergies are coming out of roles like mine, and IT and premises and so forth."
The Commission's final decision is expected in March next year.
