DD is 11mths and is in full-time cloth (except when I get lazy

) and a friend has asked me to make her nappies for her twins when they arrive. She is only 13wks preg now, so I have heaps of time, but I was wondering how many she will need. I have around 30ish, so does that mean she will need 60

or do you think will she get by with less?
TIA