From Quintessential Quintuplets Movie (1hr 15mins in):
A character was talking to her father about how he left her mother when she and her sisters were born. The father expressed that he wanted to make it up to them, but she had this to say.
最後まであなたからお母さんへの謝罪の言葉はありませんでしたね。 私はあなたを許さない。 罪滅ぼしの駒にはなりません。 あなたがお母さんから解放される日は来ないでしょう。
If I wanted to try to translate this line,
"(I) will not become a piece in your desired atonement(?)"
I don't know what 駒 means in this context and I also don't know what the subject of the sentence is since it seems like it's understood by every party involved.
What does 駒 in this context mean and what exactly is the subject of the sentence?