Yeah, because you can't create multiple array, it's fairly difficult to work with for instances of objects unless you want to constantly loop through all of your objects. Technically you can work backwards to create instances of it but that would look really weird: Basically, to do that, you'd create an Array object for each Active object and then set a variable in each Active object to the fixed value of the created Array object. After that, any time you need to store object-specific data, you'd run a loop for each of your Array objects and each of your Active objects. If the fixed ID of the Array object matches the stored ID in the Active object, you'd write your data to the Array object.
Why you'd want to ever do that with Fusion is something I don't know, but it's possible if you ever do want to assign an Array object to an Active object. What's more, I can't see how that'd improve performance in the least since you're still looping through your objects.
Anyway. Because Fusion's Array doesn't have any abilities that the normal Active is missing, the better method to do this is to create instances of your Active objects in a forward manner: Create your main Active objects followed by helper Active objects. When you create both of them, store the fixed ID of the helper Active object in the main Active object. When you have to share values or strings across them, you just run a loop for each of your main Active objects and then if the fixed value of the helper Active object equals the stored value, write your values or strings to the helper.
-Start of frame
+Create Character
+Create Helper
+Set helperID("Character") to fixed("Helper")
-Upon pressing Enter
+Start loop for each Helper
-On loop for each Character
-fixed("Helper") == helperID("Character")
+Write values and strings from Character to Helper
The 10 String variable limit per object is quite challenging to work around especially when you need to achieve the highest performance possible, but it's doable in most cases. In the above example, I'm assuming that all the Characters have strings that all the Helpers needs; otherwise, just write your strings to the Helpers and you'll never have to run the loop for each Character.
If a collision occurs, for example, Fusion automatically scopes that to the colliding objects, so when you run your loop for each Character, Fusion will only run a loop for each of the colliding Characters, not all of the existing Characters. This is incredibly efficient (and almost always necessary regardless), so understanding how this works and what Fusion is doing internally will save you a ton of time and allow you to do some really amazing things quickly and easily. I can put together an example of you'd like to see that?