I have found many instances in the past where certain marriages have not been found on Victorian Indexes.Your Robert John George Wills is another.
There were many marriages carried out by fake marriage celebrants out to make quick money in the mid to late 1800s in Central Victoria ( Castlemaine, Maryborough, Ballarat and Bendigo )
I don't like mentioning this to people but it was a fact.
This suited many couples at the time but unfortunately for family researchers it's a nightmare.
I also know that some people deliberately changed there name for whatever reason we will never know.
Regarding your questions on the marriage between R.J.G.Wills & Susannah ( possibly Bowen ) I have found referance to their eldest daughter Georgina who was one of several people that applied for Administration of the Estate of Susannah Wills of Gregory Street Ballarat who died in 1909 in Victoria.
There are 26 pages of information regarding the estate and mentions the other people involved.
They were Georgina Eltringham ( nee Wills )
Ellen Fry ( nee Wills ) Ernest john Wills, Joseph William Wills,William George Wills and John Robert Wills.
In order to get some answers you need to either go to the Public Records Office of Victoria and have all 26 pages downloaded as I have no doubt there would be some interesting information, or try typing in the link website page at the bottom of this page and download it. This will take quite considerable time.
Regarding the birth place of R.G.J.Wills my guess is he was from England. He is definitely not listed on the Pioneers Index ( one who arrived in Australia before 1840)
I can do a further search of English records and postwhatever I can find out.
Link to P.R.O.Administration info
Ian Wills ( Melbourne )
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