A family that eats together on Sundays usually started because one stubborn person insisted. Be the stubborn one.

Traditions are not organic. The family that eats together every Sunday has one person who kept setting the time, kept calling the ones who forgot and kept doing it through the years when it mildly annoyed everybody, until it became just what the family does. Nobody votes a tradition in. Somebody drags it in.

If you want something to exist in your family, be the one who picks the day and absorbs the awkwardness of asking twice. Choose a thing and do it four weeks in a row. The fourth time is usually when people start assuming it was always there.