Fusion: How to use a CustomTool value just for one Keyframe?

Hi there,
I have created a map zoom composition in fusion. The zoom target position should be flexible to be used for different places on a overview map. Everthing works fine, but I am looking for a way to minimize the places where to change values in the composition in order to adapt it to another position.

Beside the two MediaIn nodes for the overview an the detail image, there are only two values needed to define the whole setup. These are the X and the Y of the zoom center. These Values are required in different spline curves at the center position.

The CustomTool is a great option when it comes to define a static value or when to apply a keyframe curve to that value. In ma case it is not very usefull for the center point, because when I replace a fix value at the centerpoint of one of these curves with an expression, the whole existing curve is deleted.

This would force me to define every six curves within the CustomTool and to input the values there for every single curve. This does not make much sense:

Kartenzoom 01.png (267.01 KiB) Viewed 738 times

Upper left the two static values which are used in four elements.
Below you see the spline curves of the animated values. Only at the center point of the different curves the a value of the new center either X,Y or both should be applied without impacting the curve.

Is there any possibility to achieve that e.g. by using a kind of published variable which is valid for this FusionComposition?

Hi guys,
maybe my explanation was a little too complicated. Here once again a little more in detail:
The situation is as shown below. There are multiple objects with animated Parameters in a Fusion Composition but each of them has its own animation curve, but they share one value at a certain keyframe.

Below it is the X value of the zoom center which is at frame 30 the same in all of the marked objects on the left hand side. In the Inspector you see the details for rechts and links

Zoom Parameter.png (321.37 KiB) Viewed 514 times

It is no problem to assign a static value from the CustomTool see green frames, but I could not find a way to reference a global value to an animated parameter like the Center X at a single keyfame without killing the animation

BM any ideas ?