Have you checked your articles for any right to nominate an alternate director?
Pace @fisicx, there is no need for an alternate to be a shareholder unless the articles say so. Often board approval of the alternate is needed, but again it depends on the articles. If he has a right to send an alternate, there'll be nothing you can do.
Legally there's no requirement to allow anyone except the directors + sec to attend a board meeting (but check the articles, which can vary that). So these folk can probably be excluded. If they are permitted to attend and seek to exercise a veto, you can ignore them (subject to any provisions on alternates). There is probably an argument that you may not even permit them to attend.
A shadow director “lurks in the shadows”, seeking not to reveal himself as a string-puller. If there are particular non-directors consistently making director decisions, those are shadow directors, yes. But it sounds more like a gaggle of minions sent ad hoc to meetings: I'd say you have a better chance of arguing they are de facto directors. In either case they're liable as directors, and maybe suggesting that to them would make them fetch their employer.
But if they’re not actually making decisions, just relaying orders, it may be harder to establish.
Directors’ duties are non-delegable, so the absent director appears to be in breach of those. The proper plaintiff is the company. Afaik the company must show loss before it has a cause of action.
Last thing to check is that this right of veto really is in his capacity as a director, not only in his capacity as a shareholder?
