Jakob - the best thing to do is get hold of his death certificate.
However, how certain are you of Isaac's name at birth (see below)?
Also not everyone would happen to know that Tenterfield is in NSW, Australia
The best place to start is with the NSW BMD which is very good (
http://www.bdm.nsw.gov.au/) the BMD references below can be used to order certificates.
It looks as if he was married twice ? Also to a Susan Connor in Inverell?
9133/1901 WRIGHT ISAAC BEARD ANNIE EMMAVILLE
5785/1911 WRIGHT ISAAC CONNOR SUSAN INVERELL
and that he actually died in 1950 (parents noted as William & Lucy):
31953/1950 WRIGHT ISAAC WILLIAM LUCY TENTERFIELD
this should help locate his birth record BUT no Isaac's are recorded - can you be sure of his birth name (see below)?
20203/1873 WRIGHT ENOCH WILLIAM LUCY WELLINGROVE
we can find the three daughters he had with Annie...
17094/1902 WRIGHT MABEL M ISAAC ANNIE TENTERFIELD
30821/1903 WRIGHT UNA B ISAAC ANNIE INVERELL
4203/1905 WRIGHT MAUD ISAAC ANNIE INVERELL
but if he did have any children with Susan the births would be too recent for publication.
It looks as if Annie may have died at the time of Maud's birth (complications?) before Isaac remarries...
1144/1905 WRIGHT ANNIE B JAMES SARAH EMMAVILLE
No birth for Annie is apparent with these parents so the family may have been immigrants?
Several possible death records for Susan Wright (nee Connor) exist.
Several records that could be his daughters marriages appear too...
2787/1921 BRYANT GEORGE WRIGHT MABEL M INVERELL
1499/1935 BUTLER CECIL E WRIGHT MAUD E TENTERFIELD
20847/1940 MCVERNON ALEXANDER HENRY WRIGHT UNA WAVERLEY
5473/1952 KEAN HUGH REX WRIGHT UNA BETTY BONDI
