Hi John
Yes, Prepar 3d and FSX are two complete different Products. So you have to reinastall every addon airport you have. And if you have further troubles with the scenery, also check inside Prepar 3d if your new scerney is above the default ones from Prepar 3d, because those simulators show the scenerys from top to bottom in the list (in the scerery library). You see the Label "priority" and the scenery with priority 1 will be shown over the one with priority 2 and so on. (so if you are under a base layer, it won't show at all).