The row over pay and grading at Glasgow City Council is proving to be a complex and potentially costly one to resolve.

Talks have been taking place again between the council, the Scottish government and the largest council union Unison.

BBC Scotland News understands Unison is now considering the latest proposals, in a dispute where both sides have appeared firmly entrenched.

So how did we get to this stage, and what could resolve the issue?

The root of the problem is a new grading system.

This is designed to finally draw a long under a long-running row over equal pay at the council.

Even this issue was complicated. Essentially, the pay in certain jobs mostly done by women was lower than the pay in jobs deemed to be of equal value that are mostly done by men.

Settling the dispute has cost the local authority a huge amount of money - in 2022 it agreed to pay out about £770m to around 19,000 claimants, both current and former employees.

It's taken years to get the new pay and grading system to the point where it could soon be implemented.

A job evaluation programme looked at each role within the local authority and then placed them into a pay grade.

While it deals with the fundamental issues, there are winners and losers.

The council says around 11% of staff assessed so far - men and women - could see a pay cut, which in some cases is over £11,000.

Last week it promised that nobody would see their salaries fall until 2029, but unions - especially Unison - remain unhappy over any workers losing money.

Unions are also frustrated that thousands of council workers still do not know what their wages will be, as their roles have yet to be graded.

The council decided to carry out job evaluations on a phased basis as it would let them assess those in so-called primary benchmark roles - the council's most common jobs - quicker.

However that has meant workers in secondary benchmark roles - meaning groups of jobs less common but where the work is very similar - or unique roles are still unsure where they will be placed in the new structure.

There have been warnings the council could face "effective bankruptcy" if the new system is not implemented soon.

For clarity, Scottish councils cannot go bankrupt as they are under a legal duty to set a balanced budget.

But if they cannot do this - perhaps because the choices are so unpalatable - the Scottish government could send in civil servants to keep the council running.

That is a nuclear option and highly unlikely in practice at this stage.

But another nuclear option came close to being used - and its use, while a last resort, cannot be ruled out completely at this stage.

Two weeks ago, the council warned it would send out dismissal notices to all staff other than teachers. They would then be rehired under the new pay and grading system if they wanted to stay with the council.

All three council unions were angry.

The political reaction left the council in no doubt about the Scottish government's view of this development.

Meanwhile the Labour Party saw a chance to attack a leading SNP council for using the so-called "fire and rehire" tactics - which are about to become illegal from next year.

One question is whether the promise to maintain the pay of individuals can be maintained beyond 2029. In other words, is it possible to ensure no current employee sees their salary drop?

That is what Unison is seeking.

Another issue is how quickly the council can tell all employees how they will be affected by the changes. A significant minority still don't know and fear large salary cuts.

On Friday, Unison indicated it would be prepared to ballot members on the final proposals. Unite and the GMB had already said they would do this.

The chances are that a ballot by all of the main unions would end the risk of "fire and rehire" being used.

But members may well vote no to the offer. If this happens, industrial action could be on the cards later.

Solving one long-running problem has created a new one.