A panel representing WeWork’s unsecured creditors wants bankruptcy court approval to sue the flexible office space provider’s majority shareholder, SoftBank, and related parties to help recover hundreds of millions of dollars for landlords and its other unsecured creditors.

In a 160-page court document, the committee laid out perhaps the sharpest rebukes so far in WeWork’s Chapter 11 case against Japan-based investment holding company SoftBank and its CEO Masayoshi Son, among others, claiming they breached fiduciary duties because SoftBank sat “on both sides” in some deals that only sought to benefit Softbank and related parties’ interests while sacrificing those of unsecured creditors.