Relation in JOSM preset

Is there a way to create a JOSM preset that automatically adds the node to the relation?
Member_expression looks promising, but I can’t find a good guide how to use it…

Seems that any thread, any language I know - this question is enough to kill the thread.

Really, NOBODY knows how it works?

I have never tried it, sorry.

Right now I often select the things that have to go in the relation and then start the preset that creates the relation. I do this e.g. for a turn restriction. Select from way - intesection node - to way. They are all three placed in the relation, in that order. I still have to add the roles.
I guess that the member_expression is just a way to filter the “object” that you have selected before launching the preset. But don’t know for sure.

Please explain in more detail, what you want to do with the preset.
Select a node and a relation, then apply the preset to make the node a part of the relation? Do you mean it this way?

Preset code is explained here https://josm.openstreetmap.de/wiki/TaggingPresets
The default JOSM preset code is here: http://josm.openstreetmap.de/browser/josm/trunk/data/defaultpresets.xml

No, I want to create a specific preset for automatic bicycle rental station in a specific network in Warsaw and all the station should belong to a specific relation (and have some other tags set to specific values). So I have created a preset that sets all the values, but I don’t know how to add a rental station to a relation (all stations should belong to “Veturilo” relation.

What I want is a preset, that only asks for station’s name, number and capacity, automatically sets other tags (network name, operator…) and automatically adds the station to the “Veturilo” relation.

No, this is not possible with a JOSM preset.
Besides, what you describe sounds much like a superfluous “collective relation”. (http://wiki.openstreetmap.org/wiki/Relations/Relations_are_not_Categories)
You can search for those pois with a simple overpass querry: open http://overpass-turbo.eu/ click on wizard and type amenity=bicycle_rental in warsaw