you can re-run “Normalize” with a different setting (e.g. “Coreg MRIs: Hybrid SPM & ANTs) in the coreg popup and choosing “(Re-)apply (priorly) estimated normalization.” in the Normalization popup.
Since coregistrations are affine (nonlinear), it’s okay to mix methods in this step IMHO.
If none of the options coregister your images nicely, you could try to manually coregister the postops to preops e.g. using 3DSlicer.