If you have things set up so that your layer names end with a space and a number, so that they increment when you duplicate them, you should be able to use the layer's name to navigate to the other layers in the set. For example, if your layers are named "layer 1", "layer 2", etc. and your control layers are named "control 1", "control 2", etc., you could do something like this in your expressions to construct the control layer's name on the fly:
n = name.split(" ");
ctrl = thisComp.layer("control " + n[n.length-1]);
Wow, what a great idea! I love it. You really know your After Effects scripting. Thanks a lot for the great tips. The last one you gave me worked perfect.
I'm going to try it out after lunch.
Thanks so much for this. It's such a simple, elegant solution. It worked perfect.
i found also this script which you need to buy to be able to use. altough Dan's solution makes sense and very elegant, if you are not familiar writing scripts on your own,this is also a good solution;)
i found also this script which you need to buy to be able to use
Duplicate with Connections
That script is not needed with versions of AE after CS6. Copy with Property Links and Copy with Relative Property Links have been in the past several versions of AE.