Hi there,i have thought two ways for this problem.first,I know its a bit awkward but you and your fiancee know that its her child but for her to be able to put her child`s name to hers.do you think it would be easier for your fiancee to adopt her.I know its sounds silly but its just my idea and i know it complicates and other way is that you could register her again.I have a nephew who is 2 years old now and was using my sister`s ex surname,fortunately for my sister who know somebody from the birth registrar help her to change my nephews surname to hers.And my nephew`s got my sister`s surname.