27/12/2010 22:27 GMT | Updated 22/05/2015 10:12 BST

Step-Parenting: Did Sienna Take A Step Too Far?

Step-parents haven't been so vilified since the Wicked Stepmother banned Cinderella from the ball, and as the Sienna/Sadie row shows no sign of letting up, every step-parent in the land must be re-assessing their role in their partner's kids lives, writes Kelly Rose Bradford.

To recap: Sadie Frost, ex wife of Jude law and mother of three of his children, reportedly took umbrage at Sienna Miller – childless, and Law's present squeeze – escorting her seven year old son, Rudy, to the hairdressers for what we can only assume was something of a re-style.

A furious Sadie voiced her displeasure via Twitter, proclaiming: ''I think ya should get ya own child and then cut their hair!' Then, obviously still fuming days later, allegedly banned Sienna from nine-year old daughter Iris's ballet recital.

So had Sienna overstepped the mark by changing Rudy's hair?

'Yes,' says Melanie, a step-mum of two: 'Step-parents are not the mum or dad and it's mum and dad who set the parenting rules. And no matter how much you want to do something outside of those rules you just can't. And hair cuts without permission are a definite no-no.'

But Rachel, step-mum to two young girls says that with the responsibility of step-parenting comes a certain amount of 'say':

'The girls live with us and keeping relations amicable with their mum is a huge challenge, especially as her parenting style is completely different to mine and my partner's. It's a constant source of irritation and disruption, particularly when they come back from having stayed with her – it can be hard to re-establish order as it's obvious she has let them run riot. I would never try to take over her 'mother' role, but as I take more responsibility for her children than she does, I think that gives me a right to a say in their upbringing. And I won't stay quiet if she does something unacceptable!'

Linda Jones, author of Divorce and Separation - The Essential Guide (Need2Know, £8.99) says that, whilst the children should always come first, their affection should never be 'bought'. She advises:

* Step-parents should not over compensate or try to be a 'best mate'.

* If there are squabbles between the sets of parents, the step-parent should never slate the other mother or father figure in the child's life.

* Step-parents must never expect the children to take sides, and never use the kids as pawns.

But Linda's key piece of advice is something Sienna and Sadie should surely take note of:

'As much as it may rankle, always consult the other parent in decisions you make about your step-child's life - if you know they (the parents) are totally anti mobile phones, or ear piercing or certain types of clothes, do not be tempted to give in to the child's demands for them just to win them over.

'Parenting is not a popularity contest – it's your kids' (or the kids of the person you love) lives and they deserve better.'