A non-traveling relative refers to an immediate relative who has a medical condition but is not accompanying you on your trip. In certain instances, if their health significantly worsens, you might have to either cancel your journey or cut it short.
We define an immediate relative as a mother, father, sister, brother, wife, husband, partner (same or different sex), son, daughter (including fostered/adopted son or daughter), grandparent, grandchild, parent-in-law, son-in-law, daughter-in-law, sister-in-law, brother-in-law, step-parent, step-child, step-brother, step-sister, or legal guardian.