Why would a Mother change her daughter's surname by deed poll ?

Question:

Why would a Mother change her daughter's surname by deed poll ?

Best Answer - Chosen by Asker: in the UK a childs surname can only be changed by deed poll by parents with parental responsibilty or it cannot be changed until the child is 16 years old at least not legally. so if there is more than one parent with legal resopsibilty both must agree.
or a childs name can be changed is by adoption. then the name can be changed
otherwise as far as i know itcannot be changed.
however many parents call their children by many different surnames when the child goes to school and they seem to change it as often as they choose. But this is not the childs legal name.