M.,
I didn't read the last question but since you are new to Michigan you should know we have stricter child restraint laws than other states. I got this from the Michigan State Police website:
Michigan law requires:
Children from birth until age 8 be properly restrained in a child safety seat or booster seat in the vehicle, unless 4'9" tall.
Children who are eight years old but less than sixteen years old must use a safety belt no matter where they are riding in the vehicle.
INFANTS
An infant (up to one year of age) should travel in a federally approved infant safety seat that must always face the rear of the car. Facing rearward protects the infant's fragile head and neck if a crash does occur. The seat should also be semi-reclined so the baby's head does not flop forward.
TODDLERS
Convertible seats are for children up to about 4 years of age. This seat is used facing the rear while the baby is under one year old. It may be turned around to face the front when the baby is about one year old.
When children outgrow a convertible seat, they should travel in a booster seat. A booster seat makes the safety belt fit better and more comfortably.
My four year old is still in a car seat with the five point harness, but that little stinker has unbuckled the belt attaching the child seat to the car seat on more than one occasion, so I am ready to switch her to a booster. We will probably move her to the booster with the back on it which our 6 year old son has been using and get the backless one for our son.
Buckle those kids up!