Hi Eileen,
Hope everything works out for you to go in September. Don't want to put a spanner in the works and, of course, your situation may be sorted, but I noticed on the NZIS website that you can't take kids with you on a WHV. You may know this already and have other arrangements in hand, but just in case you, or others, don't know, here's the link:
http://www.immigration.govt.nz/migra...orkingholiday/
Good Luck!