Change SubForm to "Allowadditions"

I have a subform linked to the main form by a field "UniqueID". On the subform the User can click on the navigation buttons and create a new record without even knowing he did. To prevent this automatic new record creation from occurring I set the following:

                   I set the subform to AllowAdditions "NO" on the property sheet.
                   I then added a button using the wizard to Add a new record and as expected
                   it does not allow me to add a new record because AllowAdditions is set to "No".

In vba code how do I change the property of the subform from AllowAdditions "No" to AllowAdditions "yes" before I can add a nerw record.

If there is a better way to prevent the user from clicking on the navigation buttons and creating a new record wothout knowing he did, please advise me how to do this.   I will still need a "Add New Record Button" for the user to create a new record when he really wants to.

Lou