If you know that they all stay in the Castleford area - which comes under Pontefract - then this looks like Donald's death:
Donald Watson
Birth 1 August 1922 Death December quarter 1981 Pontefract, North Yorkshire, England
(posted because this does not show on free bmd)
However, if Ivy married Mr Crawshaw, that was in Dewsbury, and a possible death in Blackpool.
There is also a marriage in Pontefract for an Ivy Watson, which we would have suggested - so you have more information than we have.
If you are looking for information about living descendants then there are other websites that can help you search for them. (e.g. GenesReunited)