Other People in my Monday Hour One Scheduling

I’m trying to get my next 2 weeks of vacation planned to include some unfinished projects I have and so far I’ve been able to list all I want to do, decide how much time every single activity will take, schedule my free time, meals, dog walks, routines, etc, and I’m now adding the projects. I’ve added 2 projects so far but I feel stuck because 2 of the projects will be done by me and my father or me and my boyfriend. When I tried to ask when they would be available to complete the tasks they mentioned they don’t know so I don’t know how to plan the tasks I have with them.

I also have an issue with tasks dependency. I’m trying to create a business selling goods in Amazon. I have already listed all the activities that need to be done to put my first product in Amazon. But for one of the tasks, I need to send the products to an Amazon warehouse. The problem is that I don’t know the process to do that yet, so I added 1 hour in my calendar to review the process so that I make sure I know how’s done and how much time i need for that specific task. How can I plan everything if I’m still unclear about some processes?