The Imbolc Incident

In February, Kestrel Wallace and her family prepare to celebrate their home and one another, as they do every year for the sabbat of Imbolc. Kestrel is looking forward to the Imbolc gathering, when Grandpa will lead the family in asking for health and healing for the coming year.
But this year, Grandpa receives news about his health that affects the entire family. He will be unable to attend the gathering, and Kestrel and her cousins aren't allowed to visit him.
How can they celebrate Imbolc without Grandpa? And will Kestrel and her cousin Bran's healing altar help him?