Hi
I have now seen transcripts of the Rawmarsh registers. It would appear that John may have had some other children. Chambers is an unusual name in the Rawmarsh registers in fact John is the only Chambers as a father with the following;

Christenings in Rawmarsh with John as father, Thomas 21 Feb 1745 (day labourer), Mary 7 Aug 1748 (labourer), Elizabeth 6 Oct 1751 (Collier), Matthew 16 Aug 1770 (Pot seller)
Occupation varies slightly

There is one marriage listed;
John Chambers to Anne Sharpe 25 Jun 1745 Rawmarsh

There is a suitable Anne;
Anne Sharpe dau of Joseph Sharpe blacksmith at Rawmarsh baptised 23 03 1717

which would suit the irontrade links.

Burials;
04 09 1768 Anne CHAMBERS Rawmarsh Wife of John
13 09 1761 Elizabeth CHAMBERS Rawmarsh Daughter of John Labourer
24 04 1771 John CHAMBERS Rawmarsh

Spanners in the works are a couple of other burial entries:
03 10 1780 Elisabeth NAYLOR Rawmarsh Daughter of Widow Chambers
16 10 1771 Matthew CHAMBERS Rawmarsh Son of Sarah, a Widow
01 02 1807 Sarah CHAMBERS Rawmarsh A Widow.

But these could be explained by John marrying again after the death of Ann to a Sarah and having son Matthew Chambers in 1770 who dies 1771 and Elizabeth Naylor being a previous daughter of hers. Sarah dying in 1807

There is a very suitable marriage on IGI M00752-3
John Chambers to Sarah Nailer at Ecclesfield 11 Jul 1769

There is suitable baptism for Elizabeth Nailer at Ecclesfield 15 Aug 1762 daughter of John Nailer

So I think this is a very likely scenario.

There are quite a few siblings listed for Anne Sharpe sons and daughters of Joseph Sharpe blacksmith of Rawmarsh some baptised privately, so a man of moderate means.

There is an entry: Mary Chambers marrying Edward Wright 4 Feb 1748 Rawmarsh

Cheers Tom