@babyloner, for dynamic textures, you have complete control over how many elements are written. Just as a quick example, I expanded @carolhmj’s example to place two copies of the image side by side on click by writing the image to the dynamic texture again with an offset. This is just a simple example, but you could just capture the position of the click for each graphic added to the dynamic texture and each time you refresh, you draw each graphic into the texture. This way you can add as many graphics as you want, but you still only need one texture applied to your node material.
There is some complexity you will need to work around for a good UX as the user may want to move each graphic around independently irrespective of the order the graphics were added. You may want some UI around layers so that you can force the user to click on a graphic to make it active for manipulation to help you understand what parameters need to change. This will allow you to be able to write them into the correct position and order if you want your users to be able to change the layer stack order of the graphics.
I hope this helps with some ideas.