How do the three storylines in Act 3 complicate the main conflict of The Tempest?

In The Tempest, the main conflict
revolves around Prospero's desire to enact revenge upon Antonio, Sebastian, and Alonso. 
Prospero has set up his plan to have Ariel create a storm that grounds Alonso's ship;
however, when the men and their crew are on the island, several other events come to
play.  Prospero's plans are complicated by the fact that his daughter Miranda has fallen
in love with Alonso's son Ferdinand.  Also, Caliban has taken up with Trinculo and
Stephano and the trio are plotting to usurp Prospero.  Prospero must now consider how he
is going to reconcile Miranda's love for Ferdinand without compromising his own desires;
similarly, he must decide how to handle Caliban--should he continue to try to civilize
him or leave him to the magic of the island?  Prospero's main conflict is more in line
with tragedy; however, the other story lines have comic elements which complicate the
play.