I would like to suggest an undo button. Sometimes I accidently merge items when I didn't mean to because I was just moving one item to be next to similar ones but then I accidently merged them instead. I play a lot on a laptop that I don't have a wireless mouse for. Sometimes my finger slips or gets strained on the small track pad and when I meant to move it to one spot it accidently merges with an item I didn't mean to. I guess an alternative option would be to do a click-to-move action where you can click an item you want to move and tap the place you want to move it too as a way of confirming your choice in movement. I also have the same struggles on mobile so these features would make my play experience more enjoyable.