Yes, it is possible to replicate the 2 level workflow into a 4 levels workflow. And yes you will need new statuses.
There are currently some limitations to extending the workflow you should know.
1) If you add new types of approval role and related GuardActivityes in your workflow, there will be no way to assign users to these roles through the current UI. Currently the UI is fixed for our hard-coded Approvers and Publishers roles
2)I have to know exactly what do you want to extend in the decision activity, to tell you if it is possible. Generally you can inherit the decision activity and do somethign additional to the base execute code. Also the way we build our Workflow UI(the actions buttons on the menu) is related to parsing the workflow tree and finding the decision activities in a specific workflow status. So for example changes in the decision activity logic, might have to cause changes in our FlowchartWorkflowInspector, which can get kind of complicated. So give me some sample and i will try to help further.
3) There is currently no offical custom workflow documentation samples, apart from the xamlx files themselves. We will try to provide good samples as soon as possible in the mean time you can count on our support for specific issues.
All the best,
the Telerik team
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