Hi Leanne
Unfortunately, we at RootsChat aren't really able to help you with information for "Jimmy and May".
This is because (as well as this forum being largely for searching back-in-time - i.e. ancestors), New Zealand birth records are only able to be searched up to "today's date" - in this case 10/06/1915.
[You can though look through the NZ Birth microfiche (available at larger libraries in NZ) -- but this will only tell you name of child and year of birth registration (parents names are not included.) A booklet called the District Keys can then be consulted to determine where births were registered.]
We are also not permitted here to post information about persons who may still be living.
As there are numerous persons named May and James (Jimmy) RICHARDS it's difficult for us to even find marriage / and or death records, which might have assisted.
As I've already mentioned, the other people who have trees on the Ancestry website for the Joseph / Maria RICHARDS family, may be able to help you ... or direct you to other descendants who might have information. [Noting also that marriage details for Joseph Richards / Maria BAILEY etc. are given on those RICHARDS trees. ]
Good luck with your further searching.
~ Lu