Combined, the Harrietville-Alpine north and south fires have burned more than 30,000 hectares since they were sparked by lightning on January 21.
Department of Sustainability and Environment (DSE) firefighters Katie Peters, 19, and Steven Kadar, 34, died while fighting the north fire on Wednesday.
Mr Long said aircraft waterbombing on Thursday had helped to control some of the hot spots around the alpine north fire.
Crews are rappelling into the Mount Buffalo area on Friday to put a containment line around that blaze.
The CFA and DSE said the Harrietville-Alpine south fire had not spread much overnight.
About 50 NSW firefighters will join the 240 firefighting personnel already on the ground on Saturday.
Milder weather near the Aberfeldy fire has helped fire suppression activities, authorities say, with any more rain to ease conditions further.
The fire has burned through 84,100 hectares of mostly forest country since January 17.
Firefighters have constructed control lines on more than 300km of the 400km fire perimeter by hand, using machinery and from the air.
- AAP