Ruling on burying two people in one grave

Question:
Our brother says: There is a custom in our town, which is that when a person dies, he is placed in the grave of a relative if a year or more has passed since that relative’s death. Is this permissible?

Answer: The question is ambiguous:
If the questioner means that the new deceased is buried with the old deceased for a year and then moved, that is not permissible. Rather, he should be buried in a separate grave. It is not permissible to bury someone with previous deceased persons except out of necessity, such as extreme necessity where they have no land, or in cases of fear or when there are many deceased and the graves are insufficient. In such cases, there is no harm in burying two or three together, as the Prophet (peace and blessings be upon him) did on the day of Uhud.
Otherwise, it is obligatory that each person be separate, buried separately, with a separate grave dug for him, and buried separately, as is the recommended practice followed for the deceased of the Muslims since the time of the Prophet (peace and blessings be upon him).
However, if the questioner’s intention is that he digs a grave for a relative, and then if some of the relatives die, they are buried in this grave which was not for a deceased relative but was prepared for his relative, yet that relative did not die and this person is buried in his grave, if they permit it, there is no harm in that.
If it was prepared for Zayd, and then his relative died before Zayd died, and he was buried in Zayd’s prepared grave with the permission of his family, there is no blame in that. Yes.