I have found the following:

Were they triplets? Or just registered at the same time?

Digger - Pioneer Index. Victoria 1836-1888


Query
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Surname : McCorkell (51 matches)
Spouse Surname/Fathe : John (203119 matches)
Spouse Gvn Names/Mot : Elizabeth (184970 matches)
Total matching records: 4
--------------------

Surname: MCCORKELL
Given Names: John
Event: B
Spouse Surname/Father: John
Spouse Gvn Names/Mother: Eliza
Age:
Sex: M
Birth Place: CAMPASPE
Death Place:
Year: 1850
Reg Number: 25751
Denomination: Church of England
Parish: ST PAULS, MELBOURNE
Fiche: 376

Surname: MCCORKELL
Given Names: Sarah
Event: B
Spouse Surname/Father: John
Spouse Gvn Names/Mother: Eliza
Age:
Sex: F
Birth Place: CAMPASPE
Death Place:
Year: 1850
Reg Number: 25752
Denomination: Church of England
Parish: ST PAULS, MELBOURNE
Fiche: 376

Surname: MCCORKELL
Given Names: Mary
Event: B
Spouse Surname/Father: John
Spouse Gvn Names/Mother: Eliza
Age:
Sex: F
Birth Place: CAMPASPE
Death Place:
Year: 1850
Reg Number: 25753
Denomination: Church of England
Parish: ST PAULS, MELBOURNE
Fiche: 376

Surname: MCCORKELL
Given Names: John
Event: D
Spouse Surname/Father: John
Spouse Gvn Names/Mother: Eliza HOLMES
Age: 31
Sex:
Birth Place: MELBOURNE
Death Place:
Year: 1877
Reg Number: 7989
Denomination:
Parish:
Fiche:

Surname: MCCORKELL
Given Names: Sarah Jane
Event: M
Spouse Surname/Father: AULD
Spouse Gvn Names/Mother: John
Age:
Sex:
Birth Place: MELBOURNE
Death Place:
Year: 1868
Reg Number: 707
Denomination:
Parish:
Fiche: