If each family member takes turns "running" the family prayer time, it will relieve the burden from resting solely on the parents, teach the younger family members their prayers and ideas are important also, and will give your family a closeness, by closing off the world and bringing God into the house.
To me by allowing younger family members to offer family prayer time, devotional studies and whatnot, the parents are training the child in how to go, so he won't stray as he gets older. He feels valued and an important family member, giving him security and a great foundation for life.
Proverbs 22:6 Train up a child in the way he should go,
And when he is old he will not depart from it.
Give the parents a break and organize a schedule to help know who is "in charge" when. Hang the schedule on the fridge (like a prized test score or school paper). Make it a fun time for each person, let them be totally in charge, and remember that prayer isn't always bowing your head, it could be in song like Psalms, or in a drama or poem even. Each person gets to let the other family members see their way of worship that touches their hearts. You will learn a lot about each other also. I never knew my big burly, "grease monkey" brother could draw, until he showed us. Who knows, maybe one of your siblings have a hidden talent.