My brother was researching the derelict lock house at Stacumny (Paynes Lock House) and found that the minute books for the Grand Canal are stored in the National Archives,and was able to document the occupants of same through these,the same may apply to your family's lock house.
These books start in mid to late 1700s and record all sort of incidents on the canal,contracts for horses,fines for late barges ,prosecutions for fishing etc,but takes a great deal of research if you have the time and patience.