Several organizations have banded together to help parents talk with their children about tragedies. Braintree’s Thayer Public Library this Thursday will host the Raising Healthy Children in an Uncertain World event featuring Philip Quinn, a psychologist at South Shore Mental Health. “There have been people who live in Braintree who were at the end of the Marathon, and I know there is at least one child who is having a hard time with that,” said Elisabeth Strachan, the children’s librarian at Thayer. “But there have been a number of families that mentioned that they were there. I’m hoping [this event helps].” According to Strachan, the idea for the event was generated by Quincy Community Action Program. Anyone is welcome to attend the event, which will start at 6 p.m. in the Logan Auditorium.