I'd change 4.1.c from a vote of party members to the party demonstrating to the CoA that the party has an intent to dissolve in accordance with its internal processes.
If the CoA is a member of the party when 4.1 or 2.2 apply, somebody else (who?) needs to take over that duty.
Parties should have the obligation to report changes in membership to the CoA
Parties not fulfilling their obligations should be allowed to be sanctioned in some manner.
Would it be reasonable to say a legislator may only be in one party simultaneously?
The TIL charter includes a separate provision wherein party members that are in the cabinet or other positions requiring confidentiality may not directly or even indirectly expose sensitive information to the rest of the party members. Members must take care to avoid indirectly revealing private information, for example by opening discussion on a "broad" topic that allows non-elected members to infer what the Cabinet is discussing. This is something that should be addressed here as well.