General :: Two Tables With Data That Do Not Match?

There are 2 tables:

Table 1 has National Insurance Number, first name, last name, phone no, address.
Table 2: has National Insurance Number and email address.

Table 1 is the master table where it will link to table 2 containing the email addresses of the individuals.

However, there will be a lot of email addresses in table 2 which do not relate to any record in table 1 because I do not have the individual in my database yet.

BUT I want to keep their email address because in the future this person may enlist in my imaginary business and therefore - if they do I would have their email address!

1. Is this possible in Access?

In Excel, it would be the case of a simple vlookup from the email address field into another sheet containing the National Insurance Number and email address.

2. Would it be possible to establish a one-one relationship while enforcing referential integrity?

3. Is there a way I can establish a lookup which can be built into table 1 which can lookup the email address of a person in table 2, matching on National Insurance Numbers?

So in the future if new data is input into table 1 or 2 which results in a match of National Insurance ID numbers, the outcome would mean an email address is now paired to the corresponding individual it belongs to.