passover - How to create a Seder to accommodate a large age/education range?

My family came across an interesting problem at tonight's Seder: My dad, the leader, attempted to write a Seder that attracted everyone at different times, but the actual result ended up as a particularly bad Seder beyond the norm. Here are some details:

• The cousins' ages: 18, 16, 14, 12, 9, 7


• 18 and 16 have had an excellent Jewish day school education, and the rest haven't had more than a Sunday school-level education


• The families of 7/9 and 12/14 traditionally leave after Tzafun, which I'd assumed was out of the youngsters' exhaustion but now seems like an active decision out of a lack of interest in Barech/Hallel/Nirtzah

Here are the shticks that my dad tried to execute throughout the Seder:

• Seder bingo - everyone got a piece of paper with a 5x5 board listing various elements of the Seder. The first person to make bingo by crossing off squares as their words got said over the course of the Seder (and get us to guess all 5 of their things, without using the words themselves) won the coveted prize of being first in line for dinner. We got a first and second place winner, but then it fell apart when everyone got bingo during the Ten Plagues.


• Kid-oriented Magid - my dad's traditional Magid m.o. is to get the kids to fill in the blanks. Two problems: The 7- and 9-year-olds were too shy to contribute even the things that they did know, and the 12-year-old went off on a heavily Prince of Egypt-inspired summary of the start of the story, in which everyone else pretty much was able to zone out.


• Modern problems - after removing the 10 drops from Kos Sheini, my dad had everyone go around and list a modern problem, and we'd remove another drop for each one. The 12-year-old thought it'd be funny to name explosive diarrhea as a problem facing the world today.


• Mini-debates - at various points in the Seder, my dad asked for volunteers and assigned each of them a position to defend in 30 seconds before opening up a vote on who had the best argument. The kids had no involvement whatsoever.

Basically, our problem is this: How do we keep everyone engaged at the same time? Even the adults ended up in side conversations during the kid-oriented bits, and in a post-Seder "debriefing" held by those of us who stayed till the end acknowledged that my dad's role was more "traffic cop" than "Seder leader" tonight. Ever since he'd started planning this year's sdarim, he'd had the idea of maybe doing something different tomorrow night, since it's the exact same crowd who already did all the traditional stuff tonight.

What can we do at tomorrow's Seder that'll hold everyone's interest? For what it's worth, we're Reform, so hardly anything is off-limits. Our debriefing didn't come up with any solid ideas, so any and all suggestions are welcome!