I am not saying that is how she did it . It's just looking at blood flow possibilities .
There was the statement that she could have been conscious between shots possibly so there is no definitive sequence of what may possibly had happened .
I doubt very much that Sheila moved after the first shot at all,but someone else's blood could have dropped onto her.
Though saying that,June with all her injuries managed to walk to the window,then around the area where Sheila lay,as they were her droplets,so it wasn't impossible for June's blood to have also dropped onto Sheila. Large enough drops would land on Sheila's arm and naturally run down creating the blood pattern.