I believe you have 4 options!! - because of the funds being processed through the Council [?] Or PC Charity [?]
Sounds like there's be some evidence internally here financially.
Definently look at the Council's Finance Regs.
[Edit - I'm happy to be corrected by any other fellow Councillors on this site but I think the following apply]
1 Official Complaint to the Town Clerk (email is best) - this would need to be responded to by the Town Clerk. If there is no satisfactory outcome, you would need to cite that and request it goes to panel. It would then go to a 'Complaints Panel' which consists of Town/Parish Councillors - there should be a complaints policy online or made available.
You should request a copy of the Scheme of Delegations and Terms of Reference of Full Town Council and / or committe that took this decision IF they are not online within this communication as the Council may have breached it's delegated powers (Common occurence in my Council)
Any evidence of that is in the public interest in my opinion.
2 Go Public- however you would need strong evidence and be weary of accusations being thrown back and be careful of the tone. Keep it factual. You wouldn't actually need to name Cllrs if you reference the resolutions however if this Council is like mine, I'd suggest you save copies of minutes incase they get "pulled" out of the public domain.
Focus on lack of transparency if you do this perhaps?
3. Go to the monitoring officer but you'd have to name the 2 Councillors and be quite specific. This would be treated as confidential so you couldn't go public during this investigation - [I believe]
You could refference minutes and resolutions, any emails you've received etc.
If you are dissatisfied with the Monitoring Officer, you then need to go through the complaints process with the district and then, if still dissatisfied, you go to the LGO (Local Governements Ombusdman).
You would be arguing they are acting in their capacity as a Councillor. You would need to read the Code of Conduct and link this to "The Council"
Note due to Covid , some investigations are being delayed
4. FOI - very carefully worded and very specific. You can access internal emails hence, carefully worded. Ensure you acknowledge GDPR (names may be covered in emails are reports)
At this time, the ICO have accepted FOI's can't be dealt with within the usual time frames. Hence, it'll be delayed. You can ask for finance records, reports within "The Council"
Quite alot to think about there.