OK, i had good sleep and dream solution for your problem (but also have two bad news for you) :-)

Fist bad news: you must change again technique...

Append one CommandButton (ctlNewButton) to UserControl and set its properties (Left, Top, Width, Height) to appropriate values. Set Index property to 0 and Visible property to False. In code issue:

'At module level (in (General)/(Declarations) section)
Dim I as Integer

'In Sub AddButton
I = I + 1
Load ctlNewButton(I)
ctlNewButton(I).Top = ctlNewButton(I).Top + 30 'Pixels
ctlNewButton(I).Visible = True

Click on every button will raise click event of ctlNewButton, where you will got Index of clicked button.

Second bad news: Index (I in your case) is Integer and cannot be negative. I.e. you can load max. 32767 buttons... (Index 0 is reserved for your invisible button, but if you wanna, in the first call of AddButton you can set Visible of ctlNewButton(0) to True instead of loading new button and incrementing I).