Hi Evie,
I have seen a tree showing descendants from Thomas and Sarah, but they don't seem to match up with any of my lot so far...
However, there is a document reference in the Medway Archives that you may or may not have been aware of:
Result number 551 - Please quote Reference: S_MN_Medway_Navigation_Company_1627_to_1936/S_MN_FLf_01a on request slip.
Path: Statutory_Authorities_1627_1969/ S_MN_Medway_Navigation_Company_1627_to_1936/ 01_kcc_Accession_0085_1627_to_1912/ S_MN_02_F_Finance_1627_to_1912/ S_MN_12_FLf_Freight_Account_Ledgers_1759_to_1906/ S_MN_FLf_01a.html
Medway Navigation Company
Financial records
Freight account ledger
Arranged in order of personal clients' accounts under debtor (receipts) and creditor (expenditure) headings, giving name and place of client (e.g. William Richardson of Rotherhithe, Surrey, timber merchant, William Brown of Southborough, founder, Messrs. Baldock & Mabb of Wadhurst, East Sussex, timber merchants, Thomas Burton of Stone Street, Maidstone, timber merchant, Kemble Whatley Esq. of Hartfield, Sussex, William Collens of Brenchley, timber merchant, Sir George Kelley [cf. Kelly] of Tunbridge Wells, Thomas Swayne of Tonbridge, attorney at law), date of transaction, description of operation and freight (species of goods) (e.g. timber knees and tops from Tonbridge to Chatham and Sheerness, plank, guns and brass guns between Tonbridge and Millhall (Aylesford[?]), stones, Portland stone, ropeyarn, oats) and sum paid.
Includes front index to clients, arranged alphabetically by initial letter of surname only.
[See S/MN/Flf/1b for removed loose items]
Date: 1759-1792
Quantity: 1 volume/265ff.
I wonder of the two familys ran a timber company?