Can anyone guide me on how can i make that type of system? To be honest, the device A only has to send a 0 or a 1 (a bool type) to the other arduinos and the other arduinos will read that and do a custom simple function of turning on a led.
I think there may be a simple solution to your application which avoids all the complications of connections between the devices. You can put the 0 or 1 in the advertised manufacturer data of the peripheral, and it will broadcast with the advertising packet. You can read the manufacturer data with the two centrals without ever connecting. This architecture was used in this project:
I have also seen this architecture used in a commercial barbecue where temperature data was placed in the advertising data.
Start your work with the peripheral device which will run the code to decide on the 0 or 1 (or it can be more) and then place the value you want in the manufacturer data. Then you can use a phone with LightBlue or nrfConnect to debug that code.
When the code for the peripheral is complete and it is advertising with the manufacturer data, then you can develop the code of the devices which need to read the 1 or 0 and take action.