After Effects creating slider for objects to have the same distance when moving the slider

Question

I'm kinda new to After Effects and I'm having a hard time creating a slider that I can control to move the chat windows with the same distance. The chat windows will start at the center and only one would show up. When I move the slider, it will show up the remaining 6 chat windows. I wanted for them to have the same distance and have the flexibility to use the slider. Here's an image of what the chat windows would look like if I move the slider.

Answer 1

Here's a way to do it

Put a slider on your middle layer Add the following expression to the middle layer's position control:

xval = transform.position[0];
yval = transform.position[1];
x = xval + effect("Slider Control")("Slider");
y = yval + effect("Slider Control")("Slider");
[x,y]

Then put this on your bottom layer's position control:

xval = transform.position[0];
yval = transform.position[1];
x = xval + thisComp.layer("middle").effect("Slider Control")("Slider")*2;
y = yval + thisComp.layer("middle").effect("Slider Control")("Slider")*2;
[x,y]

Then animate the slider value.

This adjusts the x and y position of the middle image by the amount on the slider. And doubles that amount for the bottom image.