I think the expression index can help you here.
In the screenshot, I have a shape layer, with the bottom corner as the anchor point. I then have two other layers parented to it, but in the rotation values, I have added:
thisComp.layer("Shape Layer 1").transform.rotation*index;
Which is a bit extreme, as each now multiplies by their layer number (eg. *2, *3 etc…), but that’s just a case of dialing in the correct value (ie *2/10 or rather *index/10)