Blackburn has experience at all three linebacker spots and started at the weakside position in place of Beason when the Panthers played Blackburn's former team, the New York Giants, in Week 3.
Beason, who had offseason knee surgery, started the first two games after playing sparingly in the preseason.
"We're working them both. Right now, Chase has got the lead," Rivera said. "A big part of it is Chase is a little more comfortable at (that position) right now. Jon is going to continue to work and get himself back in football shape.
"He's a professional and he knows his opportunity is going to come again. He'll continue to work and do the things he's asked. I know he'll take advantage of his opportunities."
Thomas is set to reclaim his starting spot this week against the Cardinals, but Rivera said White and Florence will continue to see action.
"We're not going to forget about the other guys," Rivera said. "Melvin White has got to play. Drayton Florence has got to play. We've got a good combination going there, and these guys have got to have opportunities."
INJURY UPDATE: Defensive tackle
All three players were inactive against the Giants. Edwards appears to be the closest to returning, and Rivera said he hoped Edwards would be back at practice by now.
"Yes, but again, big guys with hamstrings, it's always a concern," Rivera said. "They tend to not heal as quick, I guess."
ROSTER MOVES: The Panthers added wide receiver
Roberson was signed by the Cleveland Browns as an undrafted rookie free agent before being waived during the preseason.
Roberson finished career at Stephen F. Austin as the school's all-time leader in catches with 221, receiving yards with 3,191 and receiving touchdowns with 39.