Yes. If you do a diffraction experiment where a particle scatters off a lattice of atoms, but leaves no trace of which atom it interacted with, then you see a d

Yes. If you do a diffraction experiment where a particle scatters off a lattice of atoms, but leaves no trace of which atom it interacted with, then you see a diffraction pattern that corresponds to the superposition of all the possibilities. If you do a modified experiment where the particle leaves one atom in a different state, then you see a different result, which corresponds to scattering off of just one atom, not the whole lattice. It doesn't matter whether you actually go and check on the atom, though. What matters is whether there's something you could check on.