What is the proper way to use a convertible infant seat as a belt positioning booster?

Yes, the seat should be secured via LATCH first, then put in child, then use seat belt

—-And, yes, this is confusing to all of us—

I’m sorry, I’m quite confused by your question.
You want to use the LATCH system AND the seat belt to tether the seat down? You can only do it one way or the other. I know with the LATCH system, you do tether the top and bottom though.
Is the child forward, or rear facing? What kind of seat do you have? (infant rear facing? convertible car seat?—what brand?)

LATCH is a great system. We only use the latch for our convertible carseat. My son is 27 months old, and forward facing.

@casheroo No, you can LATCH and seat belt.

You LATCH the car seat into place, then use the seat belt over the child/booster once the child can no longer fit the belts of the seat.

@SpatzieLover Huh? Are you saying put them in a booster and then put a seatbelt on the child like a regular seatbelt??

In some cities you can take your car seat to a local fire department or police station to make sure it is attached properly. If you don’t understand the instructions, don’t put your child in the car until you find someone who can explain it to you. An improperly used car seat can be very dangerous. Make sure you know EXACTLY how the manufacturer intended for it to be used.

I’ve never heard of using the LATCH system with a seat belt..well, unless you want to make the carseat completely void. Carseat safety is determined by testing one system or the other, when it comes to tethering them down.
All links provided that say don’t use them together. Unless I’m completely misunderstanding you.
http://www.car-safety.org/latch.html
http://babyproducts.about.com/od/carseats/f/LATCH_SB.htm
http://forum.carseatdata.org/child-car-seats/105-latch-system-seat-belt.html

@Judi Many municipalities no longer offer this service due to liability issues. ours used to and no longer does Once a year our local Children’s Hospital will offer a car seat check/inspection.

@casheroo yes, the booster seat now needs the regular seat belt to hold the child in place.

@SpatzieLover Ohh okay, I didn’t think that’s what the OP was asking, since he didn’t mention a booster…or I missed it.
I would never put my child in a booster with a seat belt. Our forward facing five point harness goes up until 65lbs, in my state you have to be in a booster until 8 years old, but my children will be in a 5 point harness until they grow out of it…we’ll probably buy an 80lb or 100lb limit 5 point harness before we put them in a booster. Not worth the risk.

@casheroo Yes, my state is the same way. We have a five point harness, but our son at age four is already out growing our current car seats.
EDIT: Our car seat is rated to 100lbs.

My niece is finally out of hers as is one nephew. But the other nephews are still in boosters with the car seat belt in use to secure them in.

@SpatzieLover ; My police department and fire department stopped doing it too. That’s why I said “In some cities.”

@Judi There isn’t a city or burb in my area that does this. That’s why I responded to what you said. Even the Children’s Hospital only does this once per year…they used to have weekly inspection times. Sad but true part of a litigation happy society

They do checks at the local police stations in my area, and at the state police, and quite a few car dealerships. Most of those people, even the cops or firemen aren’t CPST though, so they just do the bare minimum and don’t have full knowledge..they take one class and then get assigned to do it. Not people I’d trust with a carseat lol

Please get someone to show you. You can go to any number of child centers and have them show your for free. Or go to the hospital or police station and ask someone. If they can’t “officially” help you then I’m sure someone will help “unofficially”.

I am part of the infant loss/child loss community and unfortunately there are too many losses from people who get in car crashes. It is very important to learn how to do this correctly. Don’t guess and don’t just read these answers and try to figure it out.