Concept for Bonding, two centrals, one peripheral

[Pseudogelb]

Hi,

I have the following setup of devices, that I want to connect over BLE: 

1.) A device X, that executes commands from a smartphone and a second device Y and also sends notifications to them

2.) A device Y, that sends commands only to device X

3.) A smartphone, that sends commands only to device X

From my evaulation so far, the easiest way to achieve this is to set device Y and the smartphone as a central and the device X as a peripheral.

Now a further problem comes in: I want the device Y and the smartphone to be bond on the device X, such that only once a button needs 

to be pressed on the device X and until a decouppling is triggered on X or the smartphone, the devices auto-reconnect after power loss.

So my questions is, is this all achievable with device X and peripheral and the smartphone and the device Y as a central? If not, what do you recommend

as a role distribution? 

[Pseudogelb]

What makes the whole setup pretty complicated is, that normally a smartphone should be a central, but since the device X and Y needs to work without the smartphone, one of the two devices needs also to be a central.