Superclass have only a autonumber.. is it possible?

Work with IT for many years, and have lately begun looking into DB and MS
Access. So Im quite a rookie in this area.

Ok,
Got a superclass named table1. That class has only one attribute, an ID
which is an auto number.

Then I have to subclasses called table2 and table3. They have the foreign
key to ID, and a couple of other attributes.

When I add a instance to my table2, I want it to add a new auto number in my
superclass, table1. eg a new instance in table1.Is this possible at all?

It seems that I need to first add to table1, and after that use that id in
table2 or table3, and that is not possible here.

any advice here?

br
Micke