I think you should simply write what you wrote here and what you would like her to do, and be fairly specific. for example:
8am: start laundry, fix breakfast, tidy kitchen
9am: reboot laundry, read books with ds2 while I do phonics with ds5
10am: prepare snack for ds2, vac & dust main floor
You might also want to do one day's schedule at a time, or no more than one week at a time, so that you can adjust if problems arise.
Make sure your dd13 has a written schedule as well so she can say "oh that's on my schedule if bf tries to take over some of the schooling of ds5." Make sure dd and ds have desks or tables where they do their things, maybe a desk in your room so you can be supervising and bf doesn't feel she needs to get involved.
Also I would absolutely have her go home after school with her kids instead of bringing them to your house, but that's just me.
Good luck!