One year old not holding her own sippy cup

Al

So my 13 month old is refusing to hold her own sippy. Now she’s been using one exclusively for a several months now. But it’s been a cup that has a weighted straw in it, so she didn’t need to hold it up or tip it to drink. She could have it in any position and still be able to drink from it. I noticed that her cups were getting a little worn and the straw wasn’t staying in, so I thought it was a good time to transition to one without a straw. One that she would have to learn to hold up and tip to drink from. Well, she was never into holding her own bottles and now she doesn’t want to hold her cup. If she’s leaned back in my lap she can hold it (more like prop it) and drink from it, but once she drinks more than half, she has to tip it up to continue drinking. I will help her by just barely using my finger to tip it up for her but as soon as she feels that movement, she will let go completely and want me to hold it for her....if I dont tip it and let her continue drinking, she gets frustrated and will throw the cup away as if it were empty... I want to help her but I feel like it may just be something she will have to learn on her own... Any tips or tricks to get her to be able to tip her sippy up so she can drink from it on her own?