While searching for the 1848 marriage I found this and it throws up a puzzle:
The Courier-Mail (Brisbane, Qld. : 1933 - 1954) - Saturday 21 February 1948 p.8
DEATHS
SAILER.-At Cremorne, Sydney, on 19th Feb., 1948, Jean Alexander Sailer, beloved Wife of Arthur John Sailer & Sister-in-law of Mrs. Angus Macpheron, Mrs. Alex Macpherson, Mr. A. E. Rogers, Mrs. A. Annandale, & Mr. J. P. Rogers.
Arthur's sisters Edith and Florence married Angus and Alex so that is simple.
Arthur's mother Janet nee BEARD remarried to a John (no middle name) ROGERS:
5 Feb 1902/B01605 Rogers John - Sailer Janet
So, at the moment I have no idea who the other three in-laws are.
John must have married previously and had at least 2 sons and a daughter.
Marriage 1926/B39407 Annandale Alexander John - Rogers Constance Janet