Setting alpha value for closed meshes at random

Hello,

I got a skeletal mesh, which consists of different closed (not connected) “submeshes”. Now I want to set some of them to be invisible at random, when I start the game or press a button ingame.
Is there any procedural way, to acessing those individual submeshes procedurally, and seting the alpa chanel of them?
Or do I have to create alph maps for all of them? This wold get complicated, because we are talking about more tham 100 meshes.