You have to choose some attribute of your curve which is invariant under subdivision and deformation. An obvious option is the 0-1 Factor.
In the group below, the example input curve is a 4-point Bezier Circle.
(For demonstration purposes, the Mess With Curve group resamples the curve, and randomly offsets its points.)
The original factor on the curve has been stored on the instances, which look up, and are set to, the Position corresponding to their Factor on the deformed version of the curve. (You could sample the rotation as well, if wanted)
This method seems only to work in Blender 3.5 at the moment, since, on cyclic curves, there appears to be an off-by-one error in Sample Curve in (at least, my version of) Blender 3.41. If anybody can contradict this, I'd be grateful.
(Blender 3.5 beta)