With the Convention of Scottish Local Authorities (Cosla) immersed in its biggest ever crisis, Glasgow has insisted "no payment will be forthcoming" after being told the cost to those eight councils planning on walking away would be around £3.5m for legal obligations.
In a letter to his Cosla counterpart, Glasgow City Council chief executive George Black branded the bill calculation "seriously flawed".
Cosla boss Rory Mair has dismissed the claims, said Glasgow had to spell out its legal position and called for a summit of both organisations' lawyers to thrash the matter out.
It comes amid a civil war among Labour council leaders over the decision by Glasgow, Aberdeen and South Lanarkshire to totally disengage from Cosla, with five others having issued notices to quit.
But while Glasgow's leader, Gordon Matheson, has written to Labour colleagues inviting them to "move on" and claiming he was committed to working together "post-Cosla", party colleagues have condemned the rebels.
East Renfrewshire's Jim Fletcher said after Friday's crunch meeting: "I don't support the councils that are leaving.
"With 16 Labour leaders, we had control of Cosla and, with the resignations, we've given it away. It's not a particularly clever thing to have done."
The row has centred on where the power lies within the organisation, how funding to local authorities is distributed and the overall effectiveness of the body.
Glasgow, which claims Cosla's funding distribution denies it about £15 million, will spell out its vision of a breakaway organisation in the coming weeks.
Cosla insists its legal set-up means those departing were partly liable for the lease of the organisation's Edinburgh headquarters and staff costs.
But in his letter to Mr Mair, Mr Black states: "I have now taken legal advice (which) contradicts much of the advice and information you presented to the Convention.
"I am advised that the wording of the constitution does not support your interpretation of it. Even if the constitution was clearly worded, your calculation is seriously flawed.
"I believe that you were premature in presenting your assessment of the financial position and that you have misled the convention with this advice. It would be prudent for you to assume that at this stage no payment will be forthcoming from Glasgow."
Mr Mair responded: "A necessary first step would be for you to set out your interpretation of the constitution and your own calculation of Glasgow's liabilities.
"If your legal advisers would like to discuss these issues with COSLA's advisers I would be happy to make arrangements"