microsoft access training class - Move Field data between forms

I Have a customer table with the Primary Key of CustID - This is an AutoNumber. A Customer can have one or pets (details stored in another table linked via CustID)

I have a form to Add a customer then a button on this form to take me to the add Pet Form, as the pet has to relate to the Customer Form i want to carry the CustId from the first form to the second form.

For example i add a customer who's CustID = 1 who has a a pet. I click the Add Pet Form and the form opens in add mode with the field CustID on. I want the CustID to be prefilled with 1, so the records are linked.


I believe i should be able to do this with an argument - but am unsure of the code

Thanks