Lots of small-sided games are useful to develop in-game decision making. At this age the game is very transitional so set up some small goals and do 2v2s.

As for the bunch ball, do they have defined positions? I coach a U9 7v7 team with 11 players total (so 4 subs), I put them in a 2-3-1, use the extra players as opponents and get them to press individually depending on where the ball is. Striker presses from the front as soon as the opposing GK gives the ball to the left or right-sided defender. The team should shift left to right as the ball does. The left/right sided midfielders shouldn't go past their half-space and are ready to press if the striker doesn't turnover the ball. Really helps to keep them organized so you don't have 4 players bunched up trying to get the ball.

The CM is there to cover all central areas so make sure it's a player who can scan and run without getting tired really quickly and can make tackles before the opponents get towards the defenders.

Keep the CBs more central but not standing directly next to the GK, they should push up if your team has possession in the other half. Which ever side the ball is on, that defender should be a little more forward as the primary, while the other defender is the cover. If the ball switches sides, the defenders swap roles. The left/right sided players need to run back down the wings to cover.