I have a character with different parts that I want to rig. The shoes has multiple parts like: laces, sole, shoe itself etc I need to apply a subdivision surface to the shoe but I dont want to apply it to each part for efficiency reasons. What is the best way to parent or put the different parts under one object or mesh so when I apply the modifier, all children get affected? For example in Cinema 4d I put all parts of the shoe under a null (empty) and then apply a subdiv surface to that null.
Modifiers aren’t inherited. You’ll need to set modifiers individually for every object. Leaving some parts joined can simplify this somewhat (if they don’t need different modifiers, there’s not really a reason to separate them.)
There are shortcuts to add different level of subdiv to any number of selected objects at once (ctrl1, 2, etc for me, but that may depend on “interface” startup options chosen.) and you can copy modifiers easily from one object to another using the link menu (ctrl l), but the modifiers aren’t really linked, they’re just copied.
If you have something complicated enough that you really really need linked modifiers, I believe the only way to do it is to set up drivers so that you can control modifiers of multiple objects from a single value.