Parent Objects question

Hello everyone!
After quite a lot of time using parents to organize objects, I found myself tangled in what seems the need of having objects with multiple parents each. I tried to search for some solutions, but all I understood is that if I think I need objects with more than one parent I simply did something wrong.

Let me summarize my situation:

In order to check for collisions, every object that the player can collide with is children of "parent_collision".
To control the depth draw order, every objects that the player can get behind and in front of is children of "parent_depth".
To organize all objects that the player can interact with, like NPCs, doors and levers, these objects are children of "parent_interactive".
Because this parent groups a lot of objects that have a collision and have to be ordered in depth, it is children of "parent_depth", that is children of "parent_collision".

The problem is: Some of the objects have no reason to be (or shouldn't be at all) grouped together. For example, not all interactive object should be ordered in depth and not all object that are ordered in depth should have a collision.

Thanks for any help!