Ongoing Processes - Keeping notes in 1 process

I’m trying to figure out the best way to keep track of onging processes. So let say a client has Payroll on the 5th and 20th of the month, every month. If I have separate tasks then any notes that were made are attached to that task. I would like to have notes that roll forward so if there was an issue that is ongoing, all of the information is right there in the notes. I was trying to do Subtasks of subtasks but that didn’t seem to work.