How are you managing to leave the "custom menu" form in the first place? You can call @SelectTreeItem on menu options even if they are not on the currently displayed tree, so long as they are on an existing tab.

For example, in Customers.db - placing:

var aa as int
aa = @SelectTreeItem("Sample Customers Application!Application Utilities!Backup Application")
 

in the On Element Entry event of the LE "City", will run from the customers add data form, even if the application menu is not currently visible (because it is on a different tab). Since the Application menu tree always exists, any form can select those items, without closing the form's tab or navigating off the form.

 var vback as int
If @add then
{vback=@selecttreeitem("Add Data Menu!Application Menu")
vback=@selecttreeitem("StAndrews!Application Utilities!Backup Application")
 

In the code you posted your first @SelectTreeItem is moving the user off the current form. You do not need to do that. If you look at the example I posted, it selects a tree item from the application command tree without moving the user off of the form they are on. In other words, do this:

var vback as int
If @add then
{
vback=@selecttreeitem("StAndrews!Application Utilities!Backup Application")
}
 

You can automate the process completely if you incorporate a macro that types in the name of the backup file and then selects the "Accept" button.

If you want more details, let me know.