I may be wrong, but reading the Act it seems to me that it's up to the owner to notify the Owners Corporation that they have an interest in the building. This is what the Act says:
Part 2: 118 Notice to be given to owners corporation of right to cast vote at meeting
(1) Person with right to vote at meetings must notify owners corporation
A person who has an interest in a lot that, subject to this Act, gives the person a right to cast a vote either personally or by nominee at meetings of the owners corporation must notify the owners corporation in writing of that interest.
I would imagine that also applies to their entitlement to receive notices and minutes (although this IS strata law so I could be wrong).
The protocol on who can speak at EC meetings is quite clear. Any owner who is not a member of the EC can attend an EC meeting but if they wish to speak, they have to be given approval by the majority of the EC before they can do so.
Now, only one co-owner can be on the executive committee (unless they have been nominated by another owner) so they have to choose who that person is. The other person then needs to seek the approval of the EC before they can speak at any meeting. This is the section of the Act that spells that out:
Schedule 3: Part 2 – 14 Owners’ attendance at executive committee meetings
An owner … is entitled to attend a meeting of the executive committee but may not address the meeting unless authorised by resolution of the executive committee.
My advice would be to go through proper procedure the next time round and take a vote allowing the second person to speak, alerting them to the fact that this is a privilege, not a right. Make it clear if they misbehave again that the next time, they will not be permitted to address the meeting.
If the meetings are being held in a private home, you can ask them to leave. If it's a public space or common property, it depends how belligerent they are and how tough a stand you are prepared to take.
Really, your strata manager should have been across this. So why exactly are you paying for their services?