adding another middle name to 6 month olds name? how?

[SlothAttack]

how do i go about adding a 2nd middle name ? do i need to do it at the registars? DSs curent name is (example:) john james smith. but i want it to be john micheal james smith.
and do i need m husbands signiture??
thanks

[handmadeworkshop]

Hello, we changed our DSs name at 6 months too. Before 12 months is very easy as he hasn't been christened. We needed to fill out a form. If I remember rightly we didn't both need to sign. They just sent us back a new birth certificate.