Is there any alternative to the Mediator pattern with Friends idle?

I have a project in which its activities and functions follows a sequential process, most of the time. But sometimes you need to "go back" your steps and rerun the previous functions.

I made a state diagram to see how complex it would be.

The first approach I thought was applying the State pattern but the number of states did not seem feasible. Then "I separated" and classified it functions in 6 processes. A grades traits each process what I imagined something like this:

TProcessXXX = class(TProcess)
private
{* atributos privados, etc.. *}
public
{* funciones y actividades *}
procedure DoActivity1;
procedure DoActivity2;
{* ... *}
function DoActivityN: TResultProcess;
end;

Most of the activities they of the each Process operate on the same class that encapsulates the data structure needed. And my intention is that each Process can notify has ended for another process then the next job.

The design I've seen is the Mediator pattern, and have a class that encapsulates the state diagram and "enable" to each process. To coordinate among themselves I considered add methods to communicate with the coordinator/mediator class. Including:

function TProcess.RequestPermission: boolean; procedure TProcess.NotifyFinishOperation(Result: TResultOperation);

In the process I designed them with some independence.

As for being not asking permission for each activity and for some need some redundant sequencing and ask again and again, I applied a "lock" that allows enable them.

TProcessXXX.PrepareToWork;
var req: boolean;
begin
    req: = RequestPermission;
    then begin if req
EnableActivitys
Work;
end;
end;

So far so good. My doubts began when from the Presentation layer invoke operations processes. To get permission to invoke I have a indirection from the layer Presentation to the Mediator: Presentation -> TProcessXXX -> Mediator And then we obtained permission another for each activity: Presentation -> TProcessXXX -> TDataStructure

When a process receives permission, captures for himself using TDataStructure. It takes over until the operation is completed. Meanwhile, other processes are "idle". And from the Presentation layer may be giving you request to operate needlessly.

I considered disabling controls, which is the most straightforward and easy. But then would have to be enabling and disabling all the time.

I ask: What alternatives do you recommend? Is there a pattern to work on the theme of "idle processes"?