Have the parents drop the children off at the beauty shop where you have arranged for a morning of "pampering".
The girls will have their hair and their nails painted. Suitable party favors could be little inexpensive purses with nail polish or note pads and pencils inside. Ask the mothers to join you at a tea room for lunch. If given enough notice the tea room will have lunch suitable for children. The mothers and daughters enjoy a nice lunch with friends and the little girls feel very grown up.