OhNo
I think there is still some confusion. Your line training captains cannot do your LPC or OPC. They can only do your annual line check (ALC). A TRE is required to conduct your LPC. An LPC is required once a year for private or commercial ops. An OPC is required twice a year for commercial operations only and is conducted by a TRE. An ALC or OPC is not needed for private operations.
The clue is in the name. LPC is a License Proficiency Check, i.e. the bit that makes you license valid when its signed by the TRE. OPC is an Operator Proficiency Check and is not signed on your license but only in the operators internal paperwork.
Hope this helps