If you doing FO OE, then you're PIC (and instructor).

CA OE, you're still PIC (and instructor). The CA logs SIC until released to the line.

Line check from the right seat, I'd probably do PIC and instructor since ultimately the buck stops with you (the CA can also log PIC in that case since he's line qualified).

Line check from the JS, I'd do instructor and but not total time. Technically there's no FAA definition of total time, but employers might expect that to be actual pilot time. You could probably get away with PIC, but I'd take the conservative road.

Instruction includes both teaching and safety, even if you're not doing any teaching you still have a safety role. Don't believe me? Try letting a line check crew do something dumb and see how long you keep your designation.

Or just create another column for other as Dubh said.

There's no clear right or wrong answer on this stuff, so just be consistent, logical, and conservative and you'll be fine. They'll be more interested in the fact that you're a LCA than exactly how you log it.