I’m at odds with that.
In seeking a donation from my parents in the fight against childhood cancer, St. Jude Children’s Research Hospital sent personalized stickers for use on envelopes, gift packages and the like. If my parents were to give a gift, it would be from the Evanses, not the Evanss.
To form the plural of a proper name ending in s, add es, just as you would for most common nouns ending in s. Examples include addresses, bonuses, gases and lenses.
An e in Evanses has evanesced. Getting it back would allow this family to coalesce. It’s the right thing to do. If you want to keep up with the Joneses, that is.
P.S. If you receive a joint gift from baseball player Evan Longoria and actress Evan Rachel Wood, it’s from Evans.