Hi SirAfrica,
You have a problem whereby your wife may win.
I am not with Laminar Research and because of the way Steam has been created I don't support the product.
The steam version is a hybrid version whereby the product has been created by a 3rd party company taking a commercial advantage of the original development work carried out by Laminar Research. It is not the official version of X-Plane 10 or 11. The official version is and has been developed by Laminar now and in the past. There is no legal or commercial arrangements between Steam and Laminar Research to sell the Steam version.
X-Plane 11 is a totally different package to XP10. This is why it took so long to be released.
If you were able to load products between XP10 and Steam10 you were lucky. You can try loading into Steam 11. My understanding is that XP10 scenery will load into XP11 in many instances. Some aircraft may load. If the purchased aircraft information has definitive comment that it can be used in XP10 and XP11 then you may be lucky and your wife wins. My understanding is they won't.
The only way you may be able to continue using your old XP10 products is to retain both versions of your software,
Cheers
Glenn