mobile home addition

[Duane]

Hi....I have a mobile home,but its not on a slab.Ive built a few decks,but they have always been free standing..my question is what is the best approach for a addition.should i install the footings below the frost line,which is 4ft.my concern is the home shifting,but the addition not shifting.should they both shift together or is it better that just the home shifts.my home has been set for 12yrs.and i dont think is shifts very much because my front door is always good summer or winter. i would really appriciate your input....thank you...Duane