Terri, just keep reminding yourself that you have to get into a routine and it takes time (unfortunately) to do that.
What I do with my crew was to start off with everyone together for Bible, poetry, and then our storytime. During that time I would also have mine doing any handwriting or copywork they needed to do. Then, because my son struggles with working with everyone else, I zip through my youngest's phonics and math (a page or so a day) while my older two are either reading in their own Bible, reading a book, doing a typing lesson, or doing www.mathusee.com's online math drill. I get the typing and math drill already set up so the oldest two just have to go to the computer and get started. Then, I can start my son on anything he can do independently (not much because he stresses when he does his work solo), or he can proceed with piano or just reading, while my youngest does a fun educational computer game (15 min. or so) Then it's middle daughter's turn for her basics. I do short lessons with my kiddo's...for my 8 yr old I do 10-12 minutes of math, grammar, spelling, and some work in a Pathway workbook. Then I call in my son and my middle does the fun educational game, piano, or just playing with little sis while my son will do his math, grammar, Latin, Writing, and spelling. On days where he has a writing assignment, I've started dropping all the other language arts subjects so he can focus on his writing project, something he isn't keen on. I also keep his lesson to about 15-29 minutes tops...we do these basics daily so I like to keep everything short. THEN, and this is typically after lunch because I'm usually stopping somewhere on oldest's basics at lunch, resume with him after lunch, THEN, we resume with our history reading, and any activity that is left. We start our day with togetherness and reading, and that's the way we end it

.
IF your oldest is good at working alone, then she can do plenty of this stuff independently while you are working with the younger ones. You can always just have her doing some extra history reading on those days when science is scheduled...or that's when she can do her independent science work, if she has any. You can always just get some biographies on history or science, JUST to have her read during time where she isn't included in what is going on.
I hope something I said helps you out.
Alison