SubD Modeling inside Moi are the scripts of Max Smirnov https://moi3d.com/wiki/MaxScriptArchive
sSplit, sBridge, sSize + SubdD Beta 9 + ... Extrude etc
my ShortCuts are P, B, S, K, E with only these ones you can all modilized in SubD technic!

So you must have only polygons with less 6 edges
better is less 5 and solids !
sSplip is necessary else that will not work! ;)