I'm not positive but I think if you just buy ARR for PC not Steam then you can still use your same character and have it for the expansion. Your character is tied to your mogstation account so it should work no matter what platform you're on. Like I own ARR for PC and PS4 and play the same character on both, so I imagine you could play with the same character on a PC copy as you do on your Steam copy. You just can't play the PC version of HW without a PC copy because I don't think it will recognize the existence of your Steam copy. It's the same between PC and PS4. Like if you have ARR for PC but buy HW for PS4 if won't let you play it on PS4 if you don't have ARR for it too. You basically have to treat Steam like another separate platform. So in your situation I'd just recommend buying a PC copy of ARR and downloading it etc before HW arrives. I think you can get it for a decent deal now in some places.
If you do what leslie says and buy the pc copy of arr tell me if you can still log into you account. I have a friend having the same issue. You can still log in to your account, it doesn't effect your mogstation. whem u login in ur mogstation and see ur version u see PC or STEAM.. if u see PC then, no. u cannot use pc and steam version toegher.. if u read steam or something similar u can use it both(like me that have pc and ps4 version) I was told in the past that since I got arr through cheap FFXIV Gil steam and my mogstation has access to my steam (such as wallet) that I would not be able to log in from a normal pc version. Id just get the steam version.
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