Hi Kris,
You are right about the confusion. However out of the chaos you can sometimes find a trail. Along with the personal information supplied by Jo, and your finding of the wedding of Osmond Cross, I think I have found the children of Osmond. Strangely it is via the same common link to the Hebditch family.
The Will of Joseph Cross left money to the two children of his brother - Osmond. Their names were John and Elizabeth Cross. I have found the Will of John Osmond Cross - proved in London, 23/7/1845. The executor of the Will is Thomas Hebditch (builder of Tabernacle Walk, Lambeth), husband of Elizabeth Hebditch, who I believe is John Osmond Cross' sister.
The IGI has a reference for John Osmond Cross - birth, 7/10/1794, christened 26/3/1824, St Giles Cripplegate: Parents; Osmond/Jane.
This Jane could be the Joan Hebditch that Kris found in the wedding of Osmond Cross.
If these findings are correct; it looks like Osmond Cross was living in the vicinity of St Giles Cripplegate, which is the same Church that his brother Samuel was married at on 4/12/1797, to Rachel Elmes of Church Knowle, Dorset. Samuel and Rachel had 9 children, all born in London/Surrey.
Unfortunately this does not resolve the birth place of Joseph, Samuel , Osmond and Elizabeth, but i does fill in a few more pieces of the puzzle.
Cheers