To Create a New Drop-down Button from an Existing Drop-down Button

Do one of the following:

Select File > Settings > User > Customize Ribbon .

or
Right-click in the blank space in the ribbon and select Customize Ribbon from the pop-up menu.

The Customize Ribbon dialog opens.
In the list below Customize the Ribbon, navigate to the group in which you want to create the drop-down button.
In the Choose components from drop-down list, select Drop-down Buttons.
Do one of the following:

From the list below Choose components from, select the desired drop-down button and then click Add.

or
From the list below Choose components from, select and drag the desired drop-down button to the list below Customize the Ribbon.
(Optional) Do one of the following:

Click Rename and rename the new drop-down button.

or
Rename the new drop-down button in the Label field in the Properties section.
(Optional) In the Properties section, from the Visibility drop-down list, select the visibility expression.
Note: The Visibility property holds the name of a named expression that will be evaluated each time the active model is changed to determine whether the item should be displayed. The named expression should return a boolean (True or False) result in order to work properly as a Visibility property.
(Optional) Set other properties, as desired.
Click Apply.