The NRL is expected to finalise a shortlist of four candidates to fill the vacant chief executive role as John Grant defended the game's working environment amid another high-profile resignation.

The NRL's chief operating officer, Suzanne Young, resigned from her role on Friday, following chief executive Dave Smith, head of game strategy Shane Richardson and head of marketing, digital and content Lewis Pullen.

Young will finish in March after 15 months in her role, to care for her ill father.

"People turn over in organisations all the time," Grant said. "Suzanne has a very personal reason for moving on and you have to be hugely respectful of that. She has put in an enormous effort.  She has a great opportunity with the way she wants to spend her time.

"That's not the way it is going to be in the NRL. The NRL is full-on, particularly coming into the season. We will now deal with that just like we have dealt with the Shane thing. We have already begun allocating Shane' responsibilities and we will do the same with Suzanne as well."

The NRL has started interviewing an internal candidate to fill Smith's role. Head of football Todd Greenberg has emerged as the favourite to become the game's next boss, while Bulldogs boss Raelene Castle has also been linked to the position.

Grant said the NRL had finalised its list of external candidates. "We are now starting the process of talking to internal candidates," he said. "We have identified the people we would like to take forward to the next stage.

"We will go through the internal candidates to identity the people we want to take to the next stage. That will give us a shortlist. The most optimistic view I could have is that we would have a CEO in place end of February, mid-March. A much more likely scenario would be mid-March, end of April.

"We wouldn't be wanting any more than four, maximum five [on the shortlist]. It's about getting the best candidate for the job. There is at least a series of three interviews that would need to go on with that shortlist."

Grant updated club chief executives on the search for an NRL boss in a meeting in Auckland on Friday. The meeting also saw the Rugby League Players Association outline its organisational plans, a timeline for further discussions on the phasing out of the under-20s competition and marketing plans for this season.

Grant acknowledged a new chief executive may wish to transform the game's management structure.

"We have to recruit the CEO and we are down that process," Grant said. "The business goes on so you have to continue to do stuff. You have to adjust the organisation accordingly. The organisation has to work properly.

"We have already made some changes in the business to make sure we have alignment around some of the key functions. We will continue to smooth that out. And we will continue to hire."