They aren't breaking any promises if they decide to take their ball and go home.
( They ( ( ( are n't ) ( ( breaking ( any promises ) ) ( if ( they ( decide ( to ( ( ( take ( their ball ) ) and ) ( go home ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP are) (RB n't) (VP (VBG breaking) (NP (DT any) (NNS promises)) (SBAR (IN if) (S (NP (PRP they)) (VP (VBP decide) (S (VP (TO to) (VP (VP (VB take) (NP (PRP$ their) (NN ball))) (CC and) (VP (VB go) (NP (NN home))))))))))) (. .)))
If they go home they aren't breaking promises.
( ( If ( they ( go home ) ) ) ( they ( ( ( are n't ) ( breaking promises ) ) . ) ) )
(ROOT (S (SBAR (IN If) (S (NP (PRP they)) (VP (VBP go) (NP (NN home))))) (NP (PRP they)) (VP (VBP are) (RB n't) (VP (VBG breaking) (NP (NNS promises)))) (. .)))