Hi Ryan,Will the FMC software your modeling allow overlay approaches using LNAV/VNAV?Thanks,Amman.

Overlay approaches are GPS approaches, so the question is equivalent to asking about non-precision GPS approaches. But since PMDG already provides LNAV/VNAV capability there is little to do more - it is more a question to Navigraph which approaches they provide in their database. You could probably key-in such approach if missing but I don't think it would be legal in real life flying.

Yes, you can fly virtually any approach in LNAV and VNAV or in the IAN FAC and GP modes.