Mapping 3D step files in ECAD to the 3D files in MCAD

Mechanical Engineers use their library of cad files and assign pin 01 to each part. They then send it to Allegro on a board  in IDF / IDX format. From what I have read so far, the 3D step files for each PCB part can be opened  in Allegro 16.6., after some mapping needed with the footprint.

https://www.youtube.com/watch?v=7JCUcj-YC0E

https://www.youtube.com/watch?v=pctZDM8ybrE

But it seems that this is a separate 3D library in ECAD.  Does anyone have experience with this process?

I was hoping I can directly map to the 3D database of Mechanical team, instead of creating new 3D library in ECAD