Maternity: what does this purple butterfly above the crib mean?

When Millie gave birth, she named her daughters Callie and Skye. Skye stayed with her parents for three hours, inconsolable. Then, they made a big decision: the parents wanted to place Skye alongside Callie, in the same crib, so that the twins could spend time together, before leaving each other for eternity.

What does the purple butterfly mean?
Then the moment of final goodbyes arrived. But so that no one forgets that Callie had a deceased twin, the mother had a touching idea: materialize Skye with a purple butterfly stuck to Callie's cradle. A symbol that represents a baby who died after childbirth, a twin who died too soon. Today, Callie is healthy. And the violent butterfly sticker seems to be becoming more widespread, little by little. To never forget. And to know how to differentiate between families affected by a tragedy. Now you know.