I have two different configurations of a part in the same assembly. The base extrusion sketch is two arcs connected by tangent lines, and I want one of the arcs to have an in-context concentric relation to features of other parts in the assembly - different features for the two configurations.

But when (while editing one of the parts) I create the sketch relation, it gets applied to both configurations - even though I click the button "This configuration". Why? And how can I get around this?

Using SW2013 SP4.0. Thanks for any ideas.