"But that's just the nature of the business, and every negotiation has its own timeline," Sweeney told the Bruins website Thursday. "We'll find a finish line at some point in time, Brandon and Charlie will be part of our organization for a long time. We think really highly of them as players on and off the ice, we just have to find a common ground and we're working to get there."
McAvoy had 28 points (seven goals, 21 assists) last season, following 32 points (seven goals, 25 assists) in his rookie season. The 21-year-old has played 117 of a possible 162 regular-season games.
McAvoy's agent, Michael Curran, told The Athletic in remarks published this week, "The conversations have been going fine and they're still continuing. Time will come where we find a meeting place. I just don't know when it's going to be. Charlie wants to be a Bruin."
Carlo had 10 points (two goals, eight assists) in 72 games last season. The 22-year-old is plus-41 in 230 NHL games.
Bruins president Cam Neely on Aug. 3 told NBC Sports Boston they could open training camp in September without McAvoy or Carlo.
"We do have to plan and prepare for these players to not be at camp opening day," Neely said. "But we have five, six weeks hopefully to get something done. We feel like we should be able to get something done with both of those guys at numbers that make sense for us, and hopefully makes sense for them. I think we've done a really good job of kind of managing the [NHL salary cap] and making sure that we're OK to get these guys done."