I now claim the Tax Credits and Working Tax Credit for my two children and for my step daughter.
My husband had always been the main carer for his daughter and, with the mother's agreement, claimed the CHB after they separated. He had no paid employment nor did he receive any child maintenance from the mother, even though she had a good salary.
The relationship with the mother deteriorated seriously after we were married. My husband had neither PR nor was there any Residence Order in place. The mother reduced contact with us to less than half of the week and immediatey claimed and (after a protracted battle with the Rival Claims Department), was awarded the CHB. I informed the Tax Credit admin. of the situation and was told that as no one else was claiming Tax Credit for this child we would continue to receive it.
It took 7 months to get to Court and get PR and a Shared Residence Order. However, she retained the CHB.
I still claim Tax Credit for all the children in our household (including my step daughter) and, as I am now working I have also claimed the Working Tax Credit. I did get a letter from them recently with a list of questions regarding her date of birth and also informing us that "there was a dual claim for this child". I talked to them on the 'phone and was told they could see no reference to the letter "on the screen" and could not tell me why the letter had been sent to me. They noted that there was a SRO in place regarding this child and that the mother had been claiming the CHB for about a year. Haven't heard anything else from them and I continue to receive both the Tax and Working Tax Credits.
I am almost sure that the mother has either just claimed both Tax Credits, or she has been claiming them all along and they have only just picked up on it. The CHB reference number for my step daughter will have changed when she was awarded it, so maybe they haven't tied up both claims.
Anyway, can't talk to the mother (about anything!!) and don't want to put the idea in her head that she should/could claim regardless of any agreement made between her and my husband, just because she now has the CHB, so will wait and see if we hear anything from them again.
Not sure if this info will help or if it just confirms what you already know.