It's understandable that you may have been confused about people reaching out to you for UP collaborations. After all, it's natural to assume that if someone is looking for a collaboration, they would reach out to the person in charge of the UP project. However, it's important to remember that collaboration is a two-way street. If you are interested in collaborating with someone, it's important to reach out to them as well. By doing so, you can create a mutually beneficial relationship that can help both of you achieve your goals. Additionally, collaborating with others can help you learn new skills and gain valuable experience. So, if you are interested in collaborating with someone, don't hesitate to reach out and start a conversation.