What happens to your Steam purchased expansions/DLC if you unlink your account?

[Sedivh]

Hey, I have no clue where exactly to even post this question, honestly, as it pertains to a topic that is discussed but never elaborated upon anywhere I've looked.

So, my partner acquired FFXIV through steam and played it years ago, but since she moved from the US to Europe she can no longer use the account as Square-Enix is allergic to money and doesn't allow for cross-region payments.
If she were to unlink the current Square-Enix account from her steam account and create a new European account to link that steam to, what would happen to all the expansions and DLCs you purchased on steam? Will they still be usable for the new account? Does one have to buy them again somehow?

Because Steam does not allow repurchasing of something already in your library, refunds come to mind, but sadly these DLCs have been bought years ago already and far beyond the refund policy's time window.
The only other option I see is just straight up not using steam and sticking with the independent launcher.

[DiaDeem]

I believe she may be able to pay her sub through her Steam wallet, but I'm not sure. I don't think you can unlink an account. You could also explain the situation to Steam and try for a refund. SE is super BS to try to work with for this kind of thing.

[Sedivh]

I believe she may be able to pay her sub through her Steam wallet, but I'm not sure. I don't think you can unlink an account. You could also explain the situation to Steam and try for a refund. SE is super BS to try to work with for this kind of thing.

Attempting to select "Steam payment" from Mogstation itself is blocked as the website checks for whether the account's region aligns with the steam region(Steam region is Germany, Square Enix account region is North American). Unless there is some way to purchase the gametime on Steam itself I don't see this working. Any and all attempts at payments are faced with the error code stating the use of a VPN(not the case) or asking to change the address of the account, which is pointless as the country cannot be changed, only the location within it.