Hi Tom,
I am sorry to hear that. I hope your wife will recover soon.
I can fully understand your wife needs to use the same POP account on the new Surface Pro. Do you mean your wife is using Office 365 Home Premium (or University) on Surface Pro? Office 365 Home Premium is a version of Office desktop application, and it is different from the standard Office 365 business plan (Exchange Online, SharePoint Online, Lync Online). As our forum focuses on Office 365 business plan related issue and we are not masters of Surface and Office Home Premium field, I am so sorry that I could not provide the detailed instructions from my side. However, we have a specialized forum for Office 365 Home Premium and Surface Pro:
Office 365 Home Premium: answers.microsoft.com/.../office_365hp
Moreover, you can also change the category to Surface Pro, and click Apply to post this question at the Surface forum:
Surface forum: answers.microsoft.com/.../surfpro2
To provide you with better service, I suggest you post this question at those forums. Their engineers will be more proper and professional to help you resolve this issue.
Best wishes!
Regards,
Young Yang