Does burying a child with the deceased alleviate the torment of the grave for them, or does it have any merit?

It has been previously established that the Islamic legal tradition dictates burying each deceased individual in a separate grave, and it is not permissible to exhume a grave to bury another person with them. Furthermore, it is disliked to bury two deceased individuals together in one grave if they died simultaneously. Therefore, the statement that burying a child with the deceased alleviates the torment of the grave for them is incorrect, as it contradicts the Shari'a.