Here is the form and the guide document you will need to apply for your daughters naturalisation.

http://www.ukba.homeoffice.gov.uk/si...y/form_mn1.pdf

http://www.ukba.homeoffice.gov.uk/si.../guide_mn1.pdf

You apply under Section 3 (1)
• section 3 (1) any other case not listed below where it is considered to be in the child’s best interests to be granted British citizenship.

Cheers,
Iain.