afni.nimh.nih.gov

Hi Ranjan,

If that modified volume is a separate NIFTI dataset,
they could be put back together as a 5-D dataset using
3dbucket to combine the original 4, the modified 5th
and the remaining volumes:

3dbucket -prefix DSET_modified 'DSET+orig[0..3]' NEW_v4+nii 'DSET+orig[5..$]'

or as a 4-D dataset using the identical command, but
with 3dTcat:

3dTcat -prefix DSET_modified 'DSET+orig[0..3]' NEW_v4+nii 'DSET+orig[5..$]'

- rick