Yes, the Emigration Commissioners interviewed the candidates, and collected details about those candidates. The info on the Immigration paperwork currently being digitised by commercial family history website businesses and drawn from the original records of colonial administrations (eg NSW State Archives among others... ) was based on what we can now recognise as a primitive form of ID ....
Sometimes a diligent EMigration Agent sought and the candidate then obtained from a clergyman confirming identifying details about the head of a migrating family, his spouse, their children, names/ages, occupation/s, their parentage, birth places, religion, health status... So sometimes part of that info MAY have be written down on the reverse side of some individual entries, or details of male children found on their Dad's entry and daughters on Mum's. Also sometimes a person aged 14 years or older was counted as an adult (ie adult fares, so adult allocation for meals, etc) So NOT listed in family group but as a single elsewhere in the passenger manifest.
Also, look for possibke adult siblings or patents of John and Ann/e, on that passenger list ......

So a baptism certificate was often used as a form of providing identity.
JM