[odb-users] Is there some advice on recursive call back mechnism?

[Music samal]

I just  want to construct some persist class as hierarchy structure...
it's somewhat like this ,A is the supreme class  above which there are some
B s ,
B has some C s .....and it's linked with pointer
//  it looks like that
class A
{
public:
      A(string name_):name(name){}
     A(){}
#pragma db id auto
   long long id
   string name ;
#pragma db inverse(pA)
   vector<lazy_weak_ptr<B> >
   string
}
class  B
{
public:
    B(string name):{}
    B(){}
  #pragma db id auto
long long id
string name;
   #pragma db on_delete(cascade)
     lazy_shared_ptr<A>  pA
string qualifiedname;
}

as you see these classed have an number id  the  two string  members, name
and qualifiedname,
suppose there is a B has name B1, its supper class A has name A1;
so the qualifiedname is A1.B1, it are linked names according to persist
classes hierarchy...

an A object A1 can have many children Bs,  eg, B1,B2,B3  .... Also these Bs
has
  qualified names  which are  A1.B1 , A1.B2,  A1.B3...

persisting a B is easy, just get the upperclass A's qualifiedname .and
combine with B's name

if someday  I want to update A1 . and modify its name as "A2" and update
this object A

what can I do to update children B's qualifiedname using odb-provided
callback mechism ?

and if B also have many C s , C also has name and qualified name? how to
deal with it?
it's something like trigger, modify a table trigger  modifications to other
tables .I use postgres database .
can you help me????