appending internal table from another one using 7.4 syntax

Hi,

I can move stuff from 1 table 1 another one using this :

lt_result = VALUE #( for ls_origin in lt_origin ( field1 = ls_origin-field_a && '+' && ls_origin-field_b ) ).

but if "lt_result" already contains stuff and I want to append, I cannot find the correct syntax.