The business was set up in 1998 by Mr Gregan and Erica, who remains sole director.
SV Partners director Ian Purchas said that despite the closure of the two venues and 10 of the 65 staff losing their jobs, the goal was to continue trading during the administration.
The GG Leasing website lists seven Sydney coffee shops and two in Brisbane.
At its peak the company had about 30 bars, restaurants and cafes.
Mr Purchas said growth in the business had tailed off recently.
He said one additional store would not have its lease renewed at the end of this month, but that he hoped the remaining six venues would remain open.
A creditors’ meeting is scheduled for next Tuesday.
George Gregan is the Wallabies most capped player and set the record for the most matches as captain. He also was a member of the Australian team that won the 1999 world cup.