The memorial prayer Kel Malei Rachamim concludes "may they rest in peace in their resting place[s], and let us say Amen." Okay, how to say "resting place[s]." Mishkavam? Mishkaveihem? Mishkevoseihem? ...
Is the proper phrase to console a mourner always the plural המקום ינחם אתכם בתוך שאר אבלי ציון וירושלים or should it be changed depending on whom it is said to (singluar, feminine, etc.)?