To neutralize opposition, the company management co-opted several union representatives onto the board without their consent.

co-opted 是动词 co-opt 的过去式形式。co-opt 由前缀 co-（表示"共同"）和动词 opt（选择）组成，原意是"共同选择"。但在现代用法中，常指"未经对方同意而强行吸纳某人加入某个组织"，带有强制性的意味。