Technically, if the Table 1 is the parent table to Table 2, you can only relate to one record per relationship (natively).
Other than going through and updating all data to one Client record, and referencing that one.
Another way to natively achieve this would be to create the fields on Table 2 that are open for each of these values:
DOB, Email, Phone, etc.
Then you could create an automation that when a record is added to Table 2 it performs an action.
Action 1: queries Table 1 for records that match the "Contact Name" or some other identifier, and contain an Email Address, and it updates the newly created records Email field with that value.
Action 2: queries Table 1 for records that match the "Contact Name" or some other identifier, and contain a DOB, and it updates the newly created records DOB field with that value.
Action 3: Same as above, different field.. and so on.
This probably isn't the most ideal, but it would be one way to solve it natively.