Thanks for the info, Here is the FB Number - FB16226110
I use Houdini for authoring USD files which has a great USD pipeline. USD is now supported with Substance Painter, and UDIM is the standard. Unreal has UDIM support (Virtual Textures) but Unity does not which also limits extensibility with USD. If anyone is curious I fix UDIM issues through a script that appends a UDIM number to each @name attribute and creates the appropriate MaterialX shader.