Control is visualized as a control panel to the right of Front. In Frank's ComiXes it is actually a label down the right hand side of the doorway in which people sit -- just easier to draw in a cartoon environment, he says. Either the doorway itself is Control, or Control is implied as being part of the doorway there. It's not that straightforward or magical in our head. Control is a very complicated thing, and some mechanisms are automated to make it easier.
Lillian is closely associated with control, and is the fragment specifically associated with owning and controlling our hands.
So — who is Front versus who is in Control? This is malleable. We can share skills, and Control helps us do that. So someone can be in Front and either simply directing "over the shoulder" or completely lend their skills to whomever is front via the panel.
Typing is a skill we nearly all use that may actually be native to the Control panel, who knows.