I will have 7th, 9th and 10th this year ( as well as 12th, 4th, 2nd and K lol)
I teach the 7th, 9th and 10th graders vocab, latin, grammar and writing togegther. Last year we did our TOG discussion together and I will do some of it together this year but plan a separate time with my 10th grader.
They do math independently but we use a Saxon DVD program once they hit Algebra 1/2.
My 9th and 10th graders are pretty much in the same courses for everything so they do work/study together and we go over answers, tests etc together as a group.
As far as scheduling, the older kids do science and math and any other independent work while I work one on one with my younger kids. Once the younger ones are finished with me the older ones and I sit down and go through the group subjects.