I'm looking to merge the aparc+aseg.mgz with outputs from additional seg steps such as  ThalamicNuclei (e.g., ThalamicNuclei.v13.T1T2.FSvoxelSpace.mgz)

I see in history there used to be a function mergeseg, but maybe doesn't exist anymore?

I also found in freesurfer/7.4.1/trctrain/hcp separate subject folders which have aparc+aseg+thalnuc.nii.gz, which is exactly what I'm looking for, except not in the correct space (hoping to keep in the same space as the original aparg+aseg, which ThalamicNuclei.v13.T1T2.FSvoxelSpace.mgz is in).

Thank you!

Andrew