How to put it mildly, can I ask that sister to help me move things?

I think sincerity is very important. In interpersonal relationships, hypocrisy is easy to see through. Express your difficulties frankly and sincerely. When you use a sincere heart and bring a kind of energy, the other party will feel your difficulties.

You can tell your seniors that your strength is limited and your friends around you can't help you. You must explain your difficulties.

Before talking about the difficulty, you can chat with your senior sister for a while and slowly lead to this matter. Don't bring it up suddenly, and when you ask for help, also reveal the way you thank her.

Because she is a senior after all, she may have to ask more questions in her later life and study. Don't think that you don't need to cater to others if you help. Invite the seniors to drink milk tea when you are free, and then chat and express your gratitude for that help. In this way, seniors will understand you and at least increase your trust value.