From: Rabbi Moshe Sofer
To: Rabbi Kashman
The Chasam Sofer rules that relocation of remains from a cemetery subject to desecration and flooding is permitted, that bones of multiple deceased may be placed in a shared coffin provided they are separated by partitions to prevent intermingling, and that relatives who know of the relocation must observe mourning and tear their garments. He proposes a communal enactment prohibiting the Chevra Kadisha from informing relatives of the specific day of relocation, thereby relieving them of the obligation.
Source: Shu"t Chasam Sofer YD §353