Greetings from NZ.
The timeline is correct. Points 1,2 and 3 are gleaned from various documents available online, dealing with the American Revolutionary & Indians wars, also online documents in the UK archives dealing with UK Loyalist compensation claims. Under oath to the King's commissioners, Mary Girty details the events en route to Detroit. Simon Brouster (son) was born about 1772, York County, Pennsylvania, USA. Margaret Brouster was born about 1775, Westmoreland County, Pennsylvania, USA. It is reasonable to assume the parents were married shortly before these events.
Point 4 is a calculation only. At marriage on 31st Dec 1803 Martha is recorded as 22 years of age. See the record in the Drouin Collection, Quebec St Andrews church. Permission was given by Sir Robert Shore-Milnes, the then Lieutenant Governor of Lower Canada. The marriage record is online.
Point 5 Is a natural assumption since Margaret was baptised and later died 19th Jan 1792. She is buried in Sorel, Pierre-De Saurel, Quebec, Canada. Her mother Mary Girty died 27th Oct 1795 and is buried in the same town. The BMD's here are online
Point 6. This William is mentioned in some family papers dated late 19th/ early 20th century. The author was a Great Aunt of mine with a very sharp mind, even into her 80's. She also mentions subsequent siblings and the events surrounding William's (father) death in 1824 very accurately.
Point 7. The first record I have found of William & Martha, post marriage is when their daughter Martha Summers (1815-1822) was born/ baptised at St James church in Poole Dorset England. Robert Ash Summers (1818-?) and Mary Brouster (1820-?) followed. Martha the mother died 17th April 1822 in Parkstone, Poole Dorset England. William the father was missing at sea during a bad storm 24th Nov 1824. The BMD's here are available online.
The whole thrust of this is to try and ascertain Martha's parentage. If Joseph's death is passably accurate he could not have fathered Martha. It would be nice to locate a document showing what the British bought when the hostages were sold, Mary Brouster and two children or three. If three then Mary would likely be impregnated by her Indian captors. To me this has become important, Martha is my 3x Great Grandmother. There is an 11 years gap between marriage in Quebec and records in England. This is a huge gap in the understanding of my family tree
Hope that makes clear the questions.
Derek