Not really understanding the problem here? If you want to create a specific enemy then you have to pick that enemy anyway, nothing to do with families. If the animation object is in a container with the enemy then great.
Here's one scenario: When an enemyBox is hit by bullet, stop enemyBox's motion (using platform behavior) and reduce enemy's health
Let's assume the enemy object has the relevant enemy data in instance variables (health, speed, power, etc), and the enemyBox object has positioning info, collision polygon, and Platform behavior. And the enemy and enemyBox are in a container.
If I was able to use enemies and enemyBoxes families and put them into containers together, I can write the above with a single condition and 2 actions and it will apply to all enemy types. But because I can't use families with containers, I need to write this code block specifically for every enemy type.
There are tons of places in my code where I leverage families for actions to apply to all enemy types, so I foresee the issue above being replicated many times.