These are the only refs I could find for Willie Colgrave (mother Dacie). Cannot find a marriage or death for him.

Colonial Tasmanian Family Links Detail

COLGRAVE, WILLIE
Gender: Male
Birth 1882 - LAUNCESTON, Tasmania [c]


FAMILY INFORMATION
Parents:
82210 COLGRAVE ROBERT
102941 DACIE MARY

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COLGRAVE, ROBERT
Gender: Male
Birth
Marriage/Relationship: 1882 - LAUNCESTON, Tasmania ( DACIE, MARY ) [@]
Death:

FAMILY INFORMATION
Children:
66311 COLGRAVE WILLIE 1882
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DACIE, MARY
Gender: Female
Birth
Marriage/Relationship: 1882 - LAUNCESTON, Tasmania ( COLGRAVE, ROBERT ) [@]
Death:

FAMILY INFORMATION
Children:
66311 COLGRAVE WILLIE 1882



SYMBOLS
Dates of birth which do not give a place are based upon age at death or marriage and therefore may not be accurate.
@ indicates that the date given for a marriage is derived from the date of the first identified birth of a child to the two people and therefore may not be accurate. In such cases the place is derived in the same way and may not be accurate.
[AO] indicates data added, and verified from other records, by the Archives Office
[c] indicates that data is derived from christening/baptism records
[t] indicates that the data is derived from TAMIOT (Tombstone and Memorial Inscriptions of Tasmania)

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I did find this entry for Robert Arthur Colgrave. So did Mary die, did they part, did she remarry.

Name Robert Arthur Colgrave
Spouse's Name Sarah Jessie Farrant
Event Date 08 Nov 1889
Event Place Tasmania,Australia

Australia, Birth Index, 1788-1922

Name: Willie Colgrave
Birth Date: 02 Oct 1882
Father's name: Robert Colgrave
Mother's name: Mary Dacie
Birth Place: Tasmania
Registration Year: 1882
Registration Place: Launceston, Tasmania
Registration Number: 475

Australia, Death Index, 1787-1985

Name: Mary Colgrave
Birth Year: abt 1856
Age: 28
Death Date: 13 Feb 1884
Death Place: Tasmania
Registration Year: 1884
Registration Place: Launceston, Tasmania
Registration Number: 74

Australia, Marriage Index, 1788-1950
Record Image Index-only record
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Name: Sarah Jessie Farrant
Spouse Name: Arthur Robert Colgrave
Marriage Date: 08 Nov 1889
Marriage Place: Tasmania
Registration Place: Launceston, Tasmania
Registration Year: 1889
Registration Number: 876

THANKS FOR INFO SORRY ABOUT DELAY IN RESPONDING.

I UNDERSTAND THAT MARY IS BURIED IN A CEMETERY AT EVANDALE TASMANIA BUT HAVENT BEEN ABLE TO VISIT FOR A SEARCH YET ( ANY INFO WOULD BE APPRECIATED) I AM UNABLE TO LOCATE ANY INFO ON WILLIE COLGRAVE HE SHOWS UP ON SOME COLGRAVE FAMILY TREES ON LINE BUT MY QUERIES HAVE NOT DRAWN ANY RESPONSES