1) Pull KiCAD board inside FreeCAD; 2) Move the 3D model(s) and the mounting holes in MCAD; 3) Sync the kicad_pcb board file within the new design; 4) The syncing & collaboration can be done not only with KiCAD & FreeCAD, but also with KiCAD and any proprietary CADs using the STEP format as the reference Data. The MCAD designer is allowed to use his/her favorite MCAD sw. https://youtu.be/6R6UEUScjgA
A small tutorial here:
And a recent improvement:
Tracks and SilkScreen on pcb board inside FreeCAD.
For those interested in mechanical collaboration, also this my other project could be of some value:
1) Push-Pull pcb Edge between FreeCAD and KiCAD
2) Create complex footprints in FreeCAD to be pushed to KiCAD