Node to synchronize parallel branches?

Questions
1

I have a workflow where I split the flow into several parallel running branches like in the example below.

Is there any possibility to synchronize them together, so there is only one execution path proceeding after it?

If I would go into a “Send Email” node from all the “pathX” nodes in the example, it will send X emails.
But I want to execute it only one time.

3

@mnebel will every item output data? Using merge nodes or linking them together in a line would probably solve this.