The world of the gondolier is regulated by various rules, apparently outdated and anachronistic, that however have their logic, even if at times they seem incomprehensible to the contemporary man.
Therefore, if for whatever reason you would like a specific gondolier, either to accompany you and your family on a gondola tour, or for any other circumstances, you must be able to prove that you are an already existing client; this avoids any presumptions by his colleagues in performing this service requested by you, especially in such a rigidly regulated environment.
This suggestion is not meant to be a escamotage but a way of bypassing the regulations imposed.
Knowing the territory well will help you find your gondolier again, and once you have boarded his gondola for a ride, you have created the possibility of being able to use his services again in the future.
If you are really zealous, you can even have as proof of this service undertaken, a receipt or photos.