Could the oldest kind of oversee the 8 yr old? Is there a between chores and school thing you can do that will help motivate them to finish the chores? It sounds like too many things in a row for some kids.Can you have a tidy room time in late afternoon or evening? How about taking turns with things so one or two are responsible for the clearing ,and another pair in charge of tidying the rooms that week or day.It sounds like the one is doing the things but just needs the extra time? Can you break it up more like everyone pull up covers before they come down to eat breakfast.Is it after breakfast that they go and dress and finish other chores? I know what seems to work best for moms of many is to have a child or 2 assigned to one chore they do all the time or to switch off and have one or 2 in charge of them for a week at a time.
It might even help to put a positive slant on it with the 8 yr old and talk about how chores are sometimes not fun but if there is something she feels like she does extra well and would like to be put in charge of.Some kids like to vacuum.Some ids like to put groceries away and are good at organizing the cupboards etc. Of course she may so no but then again,she might surprise you!