You should tape her so you can see her reaction. Bet it would be super cute. I told my eldest DD9 and she kept it secret as I didn't want her genetic father to know. I'm now 23weeks and she told me her teacher asked her only a few days ago if I was pregnant and she didn't know what to say (it was obvious but she didn't want to lie and say no) I didn't think she would take it on board for so long to be a secret lol Bless her. Little DD4 on the other hand told everyone on Skype that mum was having another baby and when they asked she said in 30minutes!