Defining a child ILA is basically defining a normal ILA model, except that the object should be created from the parent ILA to inherit and link the state variables from its parent.
auto child = parent.NewChild("child_name");
The input and state variables from the parent ILA can be accessed by the child ILA in a similar way.
auto in_addr = child.input("InAddr");
auto buffer = child.state("Buffer");
The child ILAs can be accessed by their name.
auto child = m.child("child_name");
It can also be enumerated.
for (auto i = 0; i < m.child_num(); i++) {
auto ith_child = m.child(i);
}