  Taking the Randall-Sundrum models as background scenario, we derive
generalized Israel-Lanczos-Sen thin-shell junction conditions for systems in
which several bulk scalar fields are non-minimally coupled to gravity. We
demonstrate that the form of the junction conditions (though arguably not the
physics) depends on the choice of frame. We show that generally (in any frame
except the Einstein frame) the presence of a thin shell induces discontinuities
in the normal derivative of the scalar field, even in the absence of any direct
interaction between the thin shell and the scalar field. For some exceptional
scalar field configurations the discontinuities in the derivatives of the
metric and the scalar fields can feed back into each other and so persist even
in the absence of any thin shell of stress-energy.
