No Child should EVER be faced with such an agonising, burden of a question on whom they wish to reside with. No Child should ever be asked to make adult decisions they are not Emotionally equipped for. It is, in itself, an Emotional Welfare Risk that tears Children apart and causes serious future emotional harm. Especially if they find out "concealed Truth" after a parent has died (as I did exactly days from my 36th Birthday when clearing out my mother's house, I discovered a letter that was irrefutable evidence it had been my mother whom had lied to me for decades)!
Too late to ever challenge that cruelest of lies.
You inherit a failure to Trust anyone. It transforms your destiny forever in that, whilst you can move on, you have been left with a Legacy + Inheritance that no-one can ever be Trusted.
If you cannot Trust your own Mother for Truth, you can never Trust anyone. (Applies to Father's + really close Family members too). But Truth from your Mother is the core foundations to learning or destroying Trust.
As I often say, "TRUST! A tiny word which takes years to build but just a split second to destroy"!
I do not know how old your daughter is but it is never a question that any child should be faced with. They do not want to choose. Whilst it may be a bit different if the Child is older and really knows how to logically express what they want unfettered by influence or torn loyalties, it is still a painful division of Loyalty, other than in exceptional cases. There are plenty of ways to go about ascertaining such wishes as all so called "Guadians" should be naturally expected to have full training in.
'Guardian"! Such a precious sacred Title that should hold a deeply humble sacred duty of care. Yet it is so deeply abused because of Ego for a Power they should never have.
West Cumbrian MP, and a Journalist, are currently interviewing all people who have experienced Abuse of Power + Process as well as outright dishonesty in sworn testimony. It is Perjury and should be treated with serious legal consequences, and Summary Dismissal once evidenced. In between, they should be placed on automatic Garden Leave if the evidence available can show that it is not the case of someone who just did not like the outcome.
CAFCASS require serious intensive auditing and Investigations including release of all Complaints under the Freedom of Information Act.
Many will be "grumpy legally unfounded" complaints. But you can be sure there exists equal amounts of the opposite.
Statistics should be taken on which individual has had the most complaints logged against them too (obviously with need to take accoun of their length of employment as someone there a decade will naturally have more complaints than necessarily someone only there for a year or less)
Challenge it. Do not give up!