Well, perhaps he had become single after the adoption*** .... simply because at some point after that adoption he was no longer married ? .... separated, divorced, widowed .... Perhaps he thought it important to re-marry to find a mother for this wee lass... So many "perhaps" issues.... eg Was Henry actually Abraham and the obvious answer is :
perhaps ... *** This word in that era in NSW has a slightly different meaning from 21st sense.... in the 1880's/1890's it's meaning is more akin to our 21st C word " fostering " rather than formalising with court orders etc. Formal adoptions in NSW commenced shortly after WWI
It is not an easy task to find archival records for those 'adoptions'.... they may be for children born before their mums married, or they may be foundlings, orphans, "half-orphans" (ie one parent dies, the other has no funds coming in to keep the family together).... Sometimes these "adoptions" were
private within the family arrangements (eg grandparents raise a grandchild as though they were the birth parents, or the child is raised by aunts/uncles) (rare to find any documentary evidence)
private arrangements within a Masonic Lodge (very hard to find archive records)
Benevolent Society arrangements (see the RChat NSW Resources Board for links)
"Childless" couples taking in children whose parents were both still living, with the childless couple receiving board and lodging fees from those parents.
And, there's most likely other arrangements too... Trove newspapers has quite a number of examples of deaths in that era for young people, where that child/teenager has different surname to the family organising the funeral, and the notices mention "adopted son/daughter" within the family notice.
Cheers, JM