To be fair, Si doesn't pay for all such treats.
( ( To ( be fair ) ) ( , ( Si ( ( ( does n't ) ( pay ( for ( all ( such treats ) ) ) ) ) . ) ) ) )
(ROOT (S (S (VP (TO To) (VP (VB be) (ADJP (JJ fair))))) (, ,) (NP (NNP Si)) (VP (VBZ does) (RB n't) (VP (VB pay) (PP (IN for) (NP (DT all) (JJ such) (NN treats))))) (. .)))
Si only pays for some treats.
( Si ( only ( ( pays ( for ( some treats ) ) ) . ) ) )
(ROOT (S (NP (NNP Si)) (ADVP (RB only)) (VP (VBZ pays) (SBAR (IN for) (S (NP (DT some)) (VP (VBZ treats))))) (. .)))