children unity

["nicolas.b" <nicolas.blanpain@fr.thalesgroup.com>]

this is an example :

generic
   type Toto is private;
package Father is
...
end Father;

generic
   type Titi is private;
procedure Father.Children (...);

My question : How can i use the children unity Father.Children ?
package Inst_Father is new Father (Toto => ...);
procedure Inst_Children is new Father.Children (Titi => ...); --
compilation error ???

can you explain me,

thanks,