Joshua Jones will join its Auckland office next month.
Mr Collins takes over the role later this year.
The acting CFO gains the role.
After almost 20 years as chief executive, Louise Bond will move into the role of chairperson for PHD New Zealand.
Returning New Zealand hospital manager Ian England appointed as MercyAscot chief executive.
Mr Schlasberg takes over from Sandhya Pillay.
Helen Andrews is promoted to partner and Kate Storer to senior associate.
Greg O'Connor will lead New Zealand's largest vehicle inspection company.
Mattias Strulik joins the group's Wellington team.
He was previously assistant hotel manager (since 2015) and replaces the late Bevan McGillicuddy.