If we have two parallel threads, how to display a parallel gateway — only at the branching or also at the merging?

A parallel gateway in BPMN is depicted at a divergence point where one flow splits into multiple parallel branches, and at a convergence point where these branches come back together.

That is, if you have two parallel flows, then:

• At the divergence, the parallel gateway indicates that both flows start simultaneously.
• At the convergence, the parallel gateway indicates that both flows must complete before the process continues.

This is important for correctly understanding process synchronization and controlling their parallel execution.