S.,
Just curious, but do you have any back up on behavior issues with the male side of your family? You didn't mention whether she acts up when your grandmother/aunts see her.
My solution isn't instant, but it does work over time. Simply redirect her, explain to her what you do. Don't emphasize the bad behavior, emphasize what needs to be done, and how to do it correctly.
Keep on trucking. :) email me if you want more ideas of what to say or how to make it work. I work by the seat of my pants, because what works one day may not work the next.
Get as MUCH rest as you can! That helps too, especially with your consistency, and especially if you have no help from the rest of the family.
Good luck,
M.
PS: Attachment parenting might work out for you, especially with all three. Again, good luck.