Custom Object Remove Add Button

Hi Everyone,

On our account page, Custom object 1 is available on a related field. (Custom object 1 will be where we track samples) There are two buttons NEW and ADD on the Account page related custom object 1field.

I want our users to use only the NEW button and not the ADD button because the NEW button properly associates the custom object with the right account.

Is there a way to disable the ADD button or create a validation to prevent the ADD button from being used???

Thanks,