% per request on the list:

\showfontkerns

\setupbodyfont[dejavu]

\replaceword[more][shelfful]  [shel{ff}ul]
\replaceword[more][shelfful]  [shelf\zwnj ful]
\replaceword[more][shifffahrt][shif\zwnj ffahrt]
\replaceword[more][shifffahrt][shif{}ffahrt]
\replaceword[more][shiffling] [shiff{}ling]
\replaceword[more][shiffling] [{shiffling}]
%replaceword[more][shiffling] [{{shiffling}}] % more a test

% also: [foobar][foo{-}{-}{}bar]

\starttext
    \setreplacements[more] shelfful shifffahrt shiffling
\stoptext
