Hello Anne,
First of all: I'd like to thank you. That's one of the best documented question I ever read here on SCN, that shows you really tried to find a solution yourself. You're great.
Now to your point: I just had a look at the wiki you mentioned, and it's dealing with value nodes... so if you copied the lines of coding included in this wiki, that's probably the reason why clicking on save will not persist your data.
In method ON_NEW_FOCUS, you should have something like that:
lr_entity ?= focus_bo.
" Let's get the values for our custom table
lr_children = lr_entity->get_related_enties( <your relationship> ).
if lr_collection is not bound or lr_collection->size( ) eq 0.
if lr_entity->is_locked( ) eq abap_true.
" No values + change mode means pre-fill is necessary
" First entry:
lr_child = lr_entity->create_related_entity( <your relationship> ).
lr_child->set_property( ... ).
lr_collection->add( lr_child ).
" Do the same for other entries.
endif.
endif.
me->set_collection (lr_collection ).
Hope that helps.
Regards,
Nicolas.