Hi. What app do you use to make them?
I make mine using sketchbook pro, which is a fantastic app if you like to draw but is a bit fiddly for making siggys. I open all the elements in sketchbook pro and save them, then I open it through edit, add it to my siggy, select save a copy and then I save that to my camera roll, open up the next element and import what I've done on the siggy so far. Then I have to cut off the border. Or, if you can get png files that save straight to your camera roll then you can just import them straight into sketchbook pro. I'm going to try fiddling with photoshop on my laptop instead.