Thanks Terpe for your comments and thoughts which are, as usual, very helpful and thought provoking.

I think my initial query was really WHEN is the best time to get her name changed by whatever means and as we are due to apply for Naturalisation & registration anytime after June 7th, i would rather there were no complications, so i think we will do that first then worry about the name change after.

My wife would like to get the oath taking and dual citizenship sorted out as soon as possible. There really is no reason why my step-daughter can't change her surname unofficially for the time being. I think my concern is if there could be a complication having a UK passport in one name and getting the phillipine authorities to do the oath taking/issue another passport in her old name.

I was rather hoping someone on the forum had done this before but evidently not. Another way of looking at this is my step daughter is currently 7 and if she marries (highly likely) then will take her husbands name anyway!

The philippines embassy did give me a number for the legalisation department (0207 451 1815) who might better answer my query but as yet i have been unable to get an answer on this number. I was not aware that you could enter the philippines with the naturalisation certificate..that's intereersting.