Here’s how I manage my multiple-people costuming projects!
Here is a screenshot of what I use, Microsoft’s OneNote. I can easily stuff in pictures, to-do lists, little notes, tables, sketches and lots of other little things. I use it to store my image references, progress on each piece, to-do’s on what’s next to buy/make, my “cool things I can do if I had time” and drawings of pattern shapes.
Another tool you can use is a spreadsheet, Like Excel. I used this a ton to keep piece lists and progress on each piece. I also saw this done at the costume shop itself too.