In a recent interview with Empire, Sienna Miller opened up about how she joined 21 Bridges with the help of Chadwick Boseman. She said that the late actor produced 21 Bridges, and had been really active in trying to get her to do it. The actor stated that Boseman was a fan of her work, which was thrilling because it was reciprocated from her tenfold. Miller recalled that Boseman approached her to do the role, offered her the film, and it was at a time when she really did not want to work anymore. She asserted that she had been working non-stop and was exhausted, but then she wanted to work with him.
Sienna Miller hesitated a little as she said that she does not know whether or not to tell this story. However, she felt it is a testament to who Chadwick Boseman was. The actor mentioned that 21 Bridges was a big-budget film, and she knew that everybody understands about the pay disparity in Hollywood.
Miller asked for a number that the studio would not give her. And because she was hesitant to go back to shooting and her daughter was starting school and it was an inconvenient time, she said; 'I'll do it if I'm compensated in the right way.' And Boseman ended up donating some of his salary to get her to the number that she had asked for. She recalled that he said it was what she deserved to be paid.