Forcing to list a co-author that did not contribute after publishing
You might take a look here; and as for a more detailed response, let me focus on this one question:

Would you do some &quot;preparing steps&quot; from my side if not willing to give in?

You could ask everyone to tell you which contributions they offered based on the Contributor Roles Taxonomy (CRediT). And make sure that the CRediTs are visible in the publication as well.
On the one hand, it is possible that they will hesitate to point out their contribution in case they do not find anything worthwhile to pick from CRediT. On the other hand, you might actually end up finding one minuscule contribution of that co-author that does merit a mention according to CRediT. The &quot;objectified&quot; nature of CRediT might help to resolve such conflicts.
And if you have the CRediTs published as well, then the readership will at least know the variation in efforts of each co-author.