If you happen to have Cotton Candy(TPA), you can sub that for other sweeteners. Marshmallow will work in a pinch as well(TPA, FA, FLV are the ones I’ve used) at lower percentages. It imparts a sweet note with a little thicker “feel” which plays well in a lot of fruity juices.
If I’m missing a particular flavor from a manufacturer, but have the same flavor from another(In your example Fuji(FA) for Double Apple(CAP)) I do this: If I haven’t done a stand-alone flavor test for the flavor I want to sub into a recipe, then I take a look at the notes others have written. Based off of their findings(true to flavor profile, overly sweet, etc, etc) I’ll get the median percentage used in a mix and half that amount to use in the recipe I’m trying to adapt. I’ve found that most of the notes tend to rely on heavier percentages than what I’m used to, so I tend to be a bit more conservative in my adaptation.
Hopefully this is a little clearer than mud…Cheers!