That’s the problem. In the case cited by alfredo you need a strong Chair who advises that the partner and siblings are not owners, and therefore have no right to attend the meeting and should leave. The meeting is a meeting of owners, not owners and their entourage.
In the case where a proxy is appointed, it may be reasonable to allow both the owner and the proxy to attend, but in that case the owner should nominate who is going to speak at the meeting and stick to that.
We had a meeting some time ago where an owner wanted to bring their lawyer – we advised that they could, but the lawyer could not speak, unless they were appointed as a proxy.
Note that for companies, if you are a member/shareholder, that gives the right to attend, speak and vote at general meetings – the provisions are very specific. For some companies limited by guarantee, members of different classes only have the right to attend a meeting, and not to speak or vote.
Essentially you should not have multiple bites of the cherry, and use that to bully the other owners.