VCI Wavefunction Overlaps?

Hi,
I am hoping to compute reduced-mode anharmonic VCI wavefunctions, and obtain Franck Condon factors between various calculations, similar to Molpro’s utility:
https://www.molpro.net/manual/doku.php?id=franck-condon_calculations

Is this possible, since VCI is already internally calculating vibrational eigenstates from a Taylor expansion of the PES? ezFCF appears to only perform overlap within the harmonic approximation.

Thank you!