The Chargers signed Clifford on Wednesday.
Biadasz is out indefinitely after suffering damage to his ACL and additional injuries to his left knee Tuesday, Adam Schefter of ESPN reports.
Thornton (hamstring) is participating in Wednesday's practice, Matt McMullen of the Chiefs' official site reports.
Biadasz is expected to face a long-term absence after he suffered what is believed to be a significant knee injury during Tuesday's practice, Mike Garafolo of NFL Network reports.
Johnston (lower body) is "totally fine" and may not even miss additional practice time after making an early exit Tuesday, Adam Schefter of ESPN reports.
Johnston sustained an apparent lower-body injury during Tuesday's joint practice with the 49ers, Kris Rhim of ESPN.com reports.
Biadasz was carted off the field during Tuesday's practice with an apparent leg injury, Daniel Popper of The Athletic reports.
Herbert will get the start in Thursday's preseason game against the 49ers,Alex Insdorf of BoltBeat.com reports.
Thornton is dealing with a hamstring issue, Pete Sweeney of The Kansas City Star reports.
Thornton (undisclosed) exited Tuesday's practice on a cart, Nate Taylor of ESPN.com reports.
