I have been researching Susan Avery. I have not found much but it may be a start.
I found a record of a will for a Henry Avery in Harting, it was dated 1700 and in it he named his nephew John Avery who had 1 son and four daughters. Their names were William, Mary, Ann, Katherine and Susan. I am not very good with dates but working on the assumption that most people in those days got wed about 20. The chances are that Susan was born roundabout the same time as Thomas in 1675 so her father would have been born about 1655 and if Henrys brother was Johns father he would have been born about 1635. It sort of fits but not confirmed.
I have ordered a cd with Marriages and other data from 1536 + of Harting and hope this will shed some light and enquired into the cost for the copy of the will incase it reveals anymore info.