Well, if you had written "a Harpers' corps" it would have been more clear, yes.
As if that one corpsE belongs to many Harpers? And it's still irrellevant if it's someone from the organisation or a man named Harper or a person who played harp. The post is not about it.
Like, and I quote: 'B) Change all mentions of “our” map in dialogues with something more suitable.'
And what this sentence supposed to mean?