I'm assuming you mean apart from each other? If you gave us a schematic of the floor plan with the lp and existing 5.1 layout, it would be a help.
Depending on the width of the lp (that is, one person, two people, etc.), the room size, and depending on the speaker size, I would start with the simple rule of a couple of feet behind, a foot to a foot and a half above, and two to three feet to either side of the ear. Then adjust accordingly to find the ideal location for your particular layout (with a good es track like Gladiator). Cheers.