My toddler is rough with our puppy help?!

Any tips and tricks for teaching toddlers to behave around dogs... this might sound like a strange topic. I have a step daughter who I have 3 days a week. She's as good as gold. We have recently got a puppy, and it's like she's become crazy over the puppy and won't listen! I know it's because she's extremely excited over the new puppy but she won't leave him alone and tbh I don't know what to do. She's become so attached to the puppy that me and my partner spend the whole day having to tell her to leave the dog alone. The dog is scared of her and hides from her she won't leave him alone and won't listen. We tell her 20 times to put the dog down and she won't do it.. it's like we're talking a different language.. when she does do it she starts crying and then picks him up again two seconds later. We explained to her he's not a toy and why she can't do it over and over again but it doesn't work. The dog cries when she picks him up and hides from her I don't know what to do... she aggravates the dog and then he will get excited and then she hits him. Obviously it's hard to explain to a 3 year old why you can't be harassing a dog but we constantly tell her and she just doesn't care.. I have to keep the poor dog separate when she's here because she's just so rough and then she cries over being away from the dog :/ what would you do? It probably seems like a strange problem but it really is stressing us out (and the puppy) any tips?