I'm about to kick off this module, and the way I read it, the side quests can be successful if the PCs simply impress and work well with the Lady Devy.
If you read the background of Belhaim, the Devy's are of course an important family. Therefore it stands to reason that as a ruling family in a small town the Devy's could be faction leaders. They would heavily influence the actions and attitudes of others who are affiliated with Abadar. So depending on how the PCs handle themselves, that covers the first 3 bonus quests. And being a small town, those affiliated with Shelyn will notice how the PCs get along with those affiliated with Abadar, and as mentioned in the above posts, will influence how NPCs deal with the PCs.
