From: Rabbi Akiva Eiger
To: Unknown recipient
A vow of konam was taken on a specific piece of neveilah, which then became mixed with permitted pieces. Rabbi Akiva Eiger analyzes whether the neder's status as a davar she'yesh lo matirin prevents bitul, given the circular dependency that annulment is impossible until the underlying neveilah prohibition is itself removed. He concludes with tzarich iyun, while deriving a practical ruling that a wife's vow confirmed by her husband lacks DSHYL"M status when mixed, since annulment is outside her control.
Source: Shu"t Rabbi Akiva Eiger §65