Creating a custom extractor for alternative account number hierarchy

Hello experts I need to create a custom hierarchy datasource for a custom objects group in FI FM in order to load alternative account number hierarchy from ECC to BW. I have created a custom extractor based on the ALTKT_SKB1 and the SKB1. The following is the code used:
IF SOURCE_FIELD_3 - IOBJNM = 'ALTKT_SKB1'.
RESULT = 'INFOOBJECTNAME'.
ELSE. RESULT = SOURCE_FIELDS_3 - IOBJNM ENDIF.

The problem is , when I load it to BW, I only see the top node name and its level 1 node element names. I don't see the grand-children (leaves from GL accounts) and whatever values come after.

It looks like I need to link those nodes I see from the setnode table to the corresponding leaves from the setleaf table. any clue how this can be done? Thanks John