Step parenting advice

So my so has a daughter who has some behavioral issues and she is 7. She has a lot of sass and doesn’t like to listen but she still is a wonderful little girl who I am glad I get to be in her life. I made a point system to get her to be on her best behavior to be able to get a toy but her dad loves to spoil her because we only get her during the summer and only a weekend once or twice during the school year and she hasnt gotten to 10 points at all yet but her dad has now twice gotten her toys without her getting to ten points because he says it’s his daughter and he can do what he wants with her but I’m the one that gave up my job so I can watch her and care for her while he can work which he only gets one or two days off a week and literally works 6:30 to 8:30 at night so I do everything with her 24/7 and I am also 22 with no kids of my own and he is 32 but any helpful ideas would be greatly appreciated I know he doesn’t get her and i know sometimes should be taken with a grain of salt but I also wanna help build her into a great person but having temper tantrums over simple no and crying over being asked to do something. I know 7 is young for some things but 🆘 send some help