With the following pipeline:

stage("begin") { println "begin" }

parallel (
    "no_stage": { println "no stage" },
    
    "": { println "no name" },
    
    "with_stage": { stage("my_stage") { println "named stage" } }
)

stage("end") { println "end" }

we are getting the following display in BlueOcean:

But in the parallel step, only the third branch has a stage defined, and therefore only this one is expected to be displayed. Unfortunately all the branches are displayed even if not containing any stage.
Additionally, the name displayed for the third branch is the branch name instead of the stage name as one would have thought.

On the other hand, in the Pipeline view it is displayed as expected:

Use case: technical steps which need to run in parallel to maintain shared resources, advance timeout monitoring, etc ... doesn't have to pollute the Blue Ocean view.

May be possible to add a boolean option to the parallel step not to use branch name as default display name in Blue Ocean, and eventually make branch with no stage invisible ?