Well, you don't HAVE to switch to the LN ID or anything, I'm just trying to help you guys understand where Marines (as they've been written/played up to this point) fit into Libertonian military lore.
If you want to portray a cloak & dagger style spaceborne marine commando team, doing things that aren't typically done by the Navy, that's totally cool and might fit with the LSF ID, though a more refined name might be a good idea for that.
If it's your goal is to represent say...the space equivalent of a "Marine Air Wing", or the entirety of the Libertonian Marine Corps though, you should probably use the LN ID.
S'all I'm saying, and like before, I'm totally happy to help you figure out Libertonian military stuff so you can help refine things and get this group going. ^^