Arrange the parts to form a meaningful sentence: P: who has been troubling / Q: better than the one / R: would know the trouble / S: she who has been in trouble

The complete sentence reads: 'She who has been in trouble (S) would know the trouble (R) better than the one (Q) who has been troubling (P).' S introduces the subject with a relative clause, R provides the main verb, Q makes the comparison, and P completes with another relative clause. Hence, the correct sequence is SRQP.