Create dropdown at runtime of guide

Hello,

I'm currently creating a GUI (matlab 2017 with guide) and I would like the user to be able to press a button which will add a dropdown menu where he then can select data from. The user shall be able to add as many of these dropdowns as he wants.

My current ide is, create a button with a callback which has runns the following code:

function AddFilterStage1_Callback(hObject, eventdata, handles)
    ElementNumber=GetNewDropdownNumber(handles);
    handle.(['dropdown',num2str(ElementNumber)])=uidropdown
end

unfortunately this creates the dropdown in a new figure, not in the GUI I'm already running. I read the documentation of uidropdown and it says, that I can do uidropdown(fig) where fig = uifigure('Position', [100 100 300 250]), so naturally I tried uidropdown(handles) which didn't work out as well.

I also tried:

handle.(['dropdown',num2str(ElementNumber)])=handle.(['dropdown',num2str(ElementNumber-1)]) 

But this would not create a copy of the button instead the Element n and Element n-1 are connected to the same dropdown (so I can manipulate the same dropdown with both Elements in the Class).

Is there a different way to achieve what I want to do or what am I doing wrong?

Thank you in Advance,

Markus