Marr joins Arc in London after four years in Australia, where she worked at agencies Campaign Palace and Leo Burnett.
Parkman has spent several years working for agencies in New Zealand, including senior roles at DDB and Publicis.
The appointments follow the arrival in June of Darren Keen from The Marketing Store. Arc said further appointments will be announced in August.
Edwards said: "Our aim is to have a client services team second to none. There is nothing more important than ensuring clients' expectations are met and exceeded. Too many agencies pay lip service to client service without dealing with the real issues.
"These two appointments are a demonstration that as the major player in the sector, we will demonstrate leadership in all aspects of our business."
This article was first published on brandrepublic.com