Bricks, Masonry, Asphalt and Concrete - Room addition using existing attached garage

:coffee: My wife and I want to knock out the wall between our attached single car garage and living room to make the living room larger. The home has self supporting trusses so removing this wall isn't a problem. The garage floor is below the floor level of the rest of the home. From the dining room\kitchen there is an entrance to this garage, with a step down of aboout fifteen inches. I know I need to anchor the new footer and slab to the existing garage floor and form this up so I can backfill and make this all in one pour. Can I just drill into the existing floor where the new foundation wall is formed up and insert re-bar at that point and tie rod across and up to the turn to the area for the floor and use wire reinforcement at that level? Also, do I need to tie this to the existing floor at any point? For clarification, this garage has foundation walls on three sides. These homes were designed so that the garage could me made into an addition. I can take pictures if need be. My Brother-in-law referred to this type of floor as a slab with a "turn down footer". He is a home builder.