Hello Sue,
I don't know if this is your family, but on the
"Index to the Children's Register of State wards 1850-1893 - Victoria"
The following names appear
Alice Carey (Alice Keogh)
Margaret Carey(Margaret Keogh)
Ellen Carey(Ellen Keogh)
Johanna Carey(Johanna Keogh)
Maybe a coincidence but probably worth while having a look

Do you have the deaths of Patrick and Margaret - the parents?
Could this be a death for Margaret with fathers surname transcribed wrongly?
Maybe she died giving birth to Patrick in 1880 and her husband put the girls into care
and took the 3 boys with him
CAREY Margaret died 1880 age 31 years
born Co Limerick
Father: Jas STEOGH Mother: Mary RYAN
Reg#11630
Raylen