I am a bit confused by the dates you have mentioned.
In the post earlier this week it said "Thomas was the informant on his sister's death in 1864 and was deceased on his mother's death certificate in 1870"
Now you have these dates "disappeared from Geelong area between 1864 when he was the informant on his sister's death to 1876 when he was deceased on his Mother's death certificate"
Is this the Mother? Mary DOWLING Event: D Father: Hollighan Jame Mother: Bridget COLEMAN Age: 92 Birth Place: KILK Death Place: Year: 1876 Reg Number: 5711
I'm wondering if this is your Thomas with mother named incorrectly?The age seems to fit with his siters??? Thomas DOWLING Event: D Father: Thomas Mother: Margaret U Age: 41 Birth Place: DUBL Death Place: Year: 1870 Reg Number: 5593
Perhaps the informant was a sister Margaret? Surname: Given Names: Margaret BRAY Event: D Spouse Surname/Father: Dowling Thomas Spouse Gvn Names/Mother: Mary HOULLAHAN Age: 48 Birth Place: KILK Death Place: Year: 1876 Reg Number: 910