nope the Nintendo Dsi was released and designed after the GBA and therefore the GBA does not accept ds games..
The DS lite and the old nintendo ds play GBA games though but the Dsi DOES NOT. The GBA plays GBA games and GB games
Both cartidges are different sizes and the ds has the ds slot and the GBA slot but thr Dsi only has the ds slot.
Therefore neither can play the other games but if you bought your oldest a Ds lite it could at least play GBA games and that is all.
The Dsi is a lot better though
I say a DSi for your oldest and a Ds lite for your youngest and then they can share games
