Hi Keith,
I'm not sure if you've made progress since you posted this last July, but in case you're still working on it, I thought I'd let you know that I might be able to help here. I too am a descendant of the same Depear family of Lincolnshire (albeit through a line that diverged from yours very early on) and you might be interested in some of the research I've done and the documents I have in my possession.
In any case, you're right that Depear (sometimes rendered DePear or other ways, especially in earlier years) is not a common name in Lincolnshire, or indeed elsewhere in England. Ciderdrinker is correct that the family is ultimately of Huguenot origin – or to be more precise, Walloon Calvinists. The family name was originally De Lespiere (rendered a number of ways, including De Piere), and they settled in the area of Hatfield Chase beginning in the 1630s. They relocated to Thorney near Peterborough from the early 1650s, where a French-speaking Walloon community was established with their own church, under the protection of the Earl Russell of Bedford. Some of them were involve in the fen drainage projects both in Hatfield Chase and the Great Fen of Peterborough. There are some suggestions the De Lespiere family was among the skilled drainage workers, but it is not conclusive.
The main branch of the De Lespiere family migrated to Moulton in the late 1600s. Certainly Mathieu de Lespiere (b. 1669), who Anglicised his name to Matthew De Piere/Pear, was there by the 1690s. He first married a woman named Susannah Mann with whom he had a daughter Elizabeth, as Ciderdrinker has pointed out. He remarried to Rebeccah Fisher, and had the children whom Ciderdrinker lists, as well as another named Mark (b. 1715) whose baptismal record does not exist, but who is otherwise well attested. My line goes back to the second son John Depear, whose descendants remained in Moulton until the very end of the 1700s, after which they relocated to Holbeach. Again, Ciderdrinker appears to be correct that your Spalding Depear line goes back to the John Depear who married Mary Telford in 1776 in Spalding, and died there. However, since looking at the 1747 will of Matthew Depear, I am not so sure that this John Depear is the same as the one born 1745 in Moulton, son of the aforementioned Matthew Depear of Moulton (1708–1748) and Mary Thorpe.
As for the documents I have, you might be interested in the wills of Matthew Depear senior (1720), and possibly those of Matthew Depear junior (1747/8), and John Depear (1781). You will see in Matthew Depear junior's will that he makes his brother John a trustee and guardian of his children, and also mentions his other brothers Luke and Mark, besides his wife Mary née Thorpe and his first son Matthew, though not any other son. He even mentions the child his wife is carrying (who is later baptised Francis, but dies an infant), and makes a special provision for the case that child turns out to be a boy. Therefore I'm inclined to think his son John born 1745 must have died young despite his burial record missing. Otherwise, the omission in his will is very strange, in view of the mention of an unborn potential son. Your John Depear of Spalding may in fact be the one baptised 06 Dec 1746 in Holbeach to Mark and his wife Susannah, though I'm honestly not sure.
I have some other documents on the Depear family, and a particularly interesting one is a 1719 bill against Matthew Depear senior and his married daughter Elizabeth (b. 1701) by Susannah Mann, his first wife. The bill is by the husband of Susannah's daughter from her first marriage, an inheritance dispute.
I hope that helps, and please feel free to reach out to me privately if you're interested more in any of this.
P.S. I've not yet ascertained with certainty whether the Judith Fisher who married Daniel Depear was a sister of Rebecca Fisher, or for that matter whether Daniel Depear was a brother of Matthew Depear (b. 1669), but I like Ciderdrinker strongly suspect both to be the case. Neither Judith nor Rebecca have a baptismal record, apparently, although there is some circumstantial evidence to suggest they came from a Baptist family, so this would fit.
