A family can honor an old custom while changing the part that makes someone feel unwelcome.

Traditions and their details are not the same thing. A custom usually carries something worth keeping, and it also carries an arrangement made when the family looked different, which may now leave somebody standing outside it. Changing that part is maintenance rather than an attack. Customs that cannot be adjusted tend to be abandoned altogether.

Ask who finds the family occasion hardest and what one change would help. Keep the shape of the thing and alter the piece that leaves somebody out.