It can be done a couple ways and you're family will always be happy!
First of all, mashed potatoes are a wonderful tradition and what's a holiday without them? How frustrating to have to skip that big bowl of creamy mashed potatoes with the potential for the potato and gravy volcano!
Here are a couple solutions that should make your meals exploded again:
Start all versions by boiling your favorite kind of potatoes in water to a soft centered consistency.
Here's the difference
*one, you can literally take the potatoes out of the water, put them in the mixing bowl, add salt (about 1 TBS), margarine (about 1/4 c.), and enough water that the potatoes were boiled in to make the consistency you are looking for. Mix well and serve!
*two, you can take the potatoes out of the water, put them in the mixer, add salt and margarine and this time add either soy milk or lactose free milk or your favorite replacement "milk" until you get the consistency you are looking for.
Either way, mashed potatoes don't have to be eliminated. Yeah! All lactose free dieters can still make volcanoes to their hearts' delight.
That's not too much to ask, is it?