Burying more then one person in the same grave

Q: Salam 3alaykum brother. Is it permissible for a husband and wife to be buried together? On top of one another?

A: 

الحمد لله رب العالمين والصلاة والسلام على أشرف الأنبياء والمرسلين، سيدنا ونبينا محمد وعلى آله وصحبه أجمعين. وبعد

Imam al-Buhouti al-Hanbali said: “It is prohibited (Haram) to bury two or more in the one grave; because the Prophet ﷺ would bury every single deceased (by themselves) in a grave, and in accordance with this, the companions continued to follow the same tradition including the people that came after them. The exception to this (burying more than one person in the same grave) is only in the case of necessity; example: is for the increase of the deceased (not having enough room to bury them) and not enough people to help bury them in the fear that they will decompose, as this was the case in the battle of Uhud where the Prophet ﷺ stated: ‘Bury two or three in the one grave.’ Related by an-Nissāie.” [Kashaf Al-Qināá: 2/143] 

It is impermissible to bury more than one person in the one grave and should only be done out of necessity as stated above, and this is in accordance with the view of the Hanbali’s. 

والله اعلم.