|Don't make Baby Jesus cry.|
When signing your Christmas card/letter (or return address labels), do not sign them like so:
Merry Christmas from the Wahlund's!
If your intention is to send Christmas greetings on behalf of your entire family, then you want your last name to be plural, not possessive. For example:
Merry Christmas from the Wahlunds! means there is more than one Wahlund wishing you a Merry Christmas. In fact, the entire Wahlund family wishes you a Merry Christmas!
The possessive form, on the other hand, indicates that something belonging to the Wahlund family is wishing you a Merry Christmas. Merry Christmas from the Wahlund's... what? The Wahlund's cat? The Wahlund's dog? The Wahlund's thermonuclear bomb facility?
If your last name ends with an 's' or 'z', then your best bet is to use a workaround such as, "Merry Christmas from the Glass family!" Or you could add an -es. But for the love of all that is holy and innocent, do not use an apostrophe to create a plural form of a surname. Please.
Baby Jesus will thank you.
Someone who has seen this on her received Christmas cards entirely too often.