Can you give your child a different surname than yours or their dad's?

[Starfish]

DH and I are going to change our surname to MIL's (from our current double-barrel of my father's and FIL's). The process takes a while and costs quite a bit (especially as it's going to be a whole family thing). If DS is born before the whole thing is sorted, am I allowed to give him MIL's surname, even if it's not officially ours yet?

[LionsandBears]

Yes. You can name your child whatever you like, within reason. Look up the births, deaths & marriages site in your state.