Can the forum software be upgraded to add (OP) in caps after the user handle so to better know the original poster replies.
It can be doable or non-doable. You should know that the forum uses the SMF software that has some drawbacks in terms of new features and so forth. Even it is doable, I think it is unnecessary.
I know that the original poster replies are written by his\her name but you have to concentrate to find the name of the poster.
You don't have to concentrate too much. What you must do to find OP's username is click on the first page, scroll up to the opening post and get that username.
It is a must-do step even you don't aim at finding OP's username. It's unacceptable when people write post to do what they call as joining discussion but don't mind to read what is raised by OP. If they do care about it, they should read OP, the first page and get username already. In addition, to catch what's going on in the dicussion, they should read the last page(s) of that topic as well.