Double door folding slide animation

I’m trying to create a door property that mimics the folding mechanism of old bus entry doors (Figure 1), where two panels are linked and fold together, but I’m having trouble setting up the open/close property.

The scene structure is shown in Figure 2. For user convenience, I’d like to create the door open/close property on the root.

However, with the steps I know, it doesn’t work correctly.
If anyone knows a solution that works with the structure in Figure 2, or the correct procedure, I’d greatly appreciate your advice.

For reference, the following steps work fine without errors for a simple single swing door or sliding window, but not for the folding bus-style door.

<My Steps> 1. Create a new property (Door_open) on the root. 2. Set the Door_open property to 100%. 3. Adjust the properties of the Door_L and Door_R objects so that the doors fold and reach the fully open position (X, Z, Y-Rotate). 4. Open the Property Hierarchy tab and drag & drop each axis into the “Sub-Components” of the Door_open property. 5. ERC Freeze the Door_open property.

Any advice would be very helpful.