may be presumed to cover more than one parish, since in his letter he refers to the living Wickham might have had as *a* family living, not *the* family living, which would have been more correct had there only been one parish. Charlotte might well know this from Lady Catherine, who would be quite capable of enlarging upon her nephew's wealth and status, and might think it possible that Darcy could be prevailed on to offer Mr Collins a better living. (Mr Collins could have retained Hunsford too, if he put in and paid a pittance to a curate). This would both increase the Collins' income and get Charlotte out from under Lady Catherine, so you can see why she might want it. Whether Darcy had any other influence in the Church could only be specualtion.