Hi Christopher,
Thank you for your reply.
I'm not sure if I can set it at the row level (in fact this is what I'm asking here).
ATM I'm using this method which set the leaf as the last column.
alv_cfg_table TYPE REF TO cl_salv_wd_config_table.
wd_this->alv_cfg_table->if_salv_wd_table_hierarchy~set_last_hier_column_as_leaf( abap_true ).