A sister saves her brothers, a love is found, lost, and found again, and you put an “o” in front of everything to be polite.
and tried hard to avoid 
causing trouble for her,
así que se comportaban muy bien 
para no causarle molestias.
y por eso procuraban 
portarse bien y no molestarla.
e tentavam não causar
 problemas para ela.