Hi, If there is: struct FXWindow { FXWindow(FXWindow *parent=0); }; ... and each FXWindow instance maintains a list of its children, and deletes its children when it gets deleted, then how do I apply custodian & ward to ensure that when the parent instance is deleted, python knows not to delete the children? Something like: class_< FXWindow >("FXWindow", init< FXWindow*>()[with_custodian_and_ward_postcall<1,2>()]) BTW the docs on the reference page for with_custodian_and_ward are confusing - the text suggests that the first arg determines the life of the second, whereas the code for return_internal_reference() is pretty clear that the second arg determines the life of the first. I am assuming that the latter is the correct orientation? Cheers, Niall