Of course you can.
On the parent part file define an equation where you define a variable:
Example: "Rod_Diam"= 20
On the child part file define an equation where you define a variable referencing the first one.
cylinder.Part is the parent part file name.
Create your features as you usually do. On any dimension you create you have the option "Link Value". This option allows you to link the dimension value to a variable. "Unlink value" breaks the reference.
Whenever you change the variable value on the parent part all the dependant features are updated including the ones in child parts if open in the editor. If parent part and child part are used in an assembly you will get what you want. These variables can be used also in mating relations, component arrays, etc. It's a very powerful feature.
I hope this helps...