Two West End concert perfs of Stephen Sondheim tuners are among the new additions to the sked of the Donmar Warehouse’s “Sondheim at 80” celebration of the composer-lyricist.

“Promises, Promises” helmer Rob Ashford will direct “Merrily We Roll Along,” with a cast including Daniel Evans (“Sunday in the Park with George”), while Jamie Lloyd (“Piaf”) directs “Company” with Adrian Lester, among other thesps. Both Ashford and Lloyd are associate directors of the Donmar.

Also added to the fest lineup are two public conversations, one between current Donmar a.d. Michael Grandage and former a.d. Sam Mendes about the Donmar’s history with Sondheim tuners (set for Sept. 16), and another between Sondheim and Variety’s David Benedict (skedded for Oct. 11).

Also announced is the full cast of “Passion,” the Donmar’s fall revival of the 1994 Sondheim musical to be helmed by Lloyd. Scarlett Strallen and David Thaxton are among the thesps joining topliner Elena Roger (“Evita”) in the show, which runs Sept. 10-Nov. 27.

“Merrily” and “Company” will each play two same-day perfs at the Queen’s Theater, with “Merrily” set for Oct. 31 and “Company” for Nov. 7.