Who is responsible for creating the br-lan bridge?

Hi, everyone, I have a question. Who is responsible for creating the br-lan bridge? And it will add all the NICs (such as eth0 eth1 and etc.) to the br-lan bridge. What are the adding rules?For example, does enp1s0 NIC will be added to the bridge?

It is created from the "/etc/init.d/network" script, according to the configuration at "/etc/config/network".