I'm Trudy.
And if she's in Edmonton or surrounding area feel free to have her email me. I'm also periodically down in the Lacombe/Red Deer area, and out at Spruce Grove firehall clinics from time to time.
I'm not inclined to register just to post, but I'm going to PM you an email address you can pass on to her if she's near me at all. Also, you're welcome to copy & paste the remainder of this post and simply post it as "you asked a carseat tech because you weren't sure yourself, and this is what you were told" I've tried to word it like it was written generically and not that I went and read the thread itself.
A 17lb 7mo old child is both under the weight limits and under the minimum age to ff in any of the combination seats available in Canada. At that size and particularly that age, there is an exponentially bigger risk of severe injury or death if they're involved in a collision. Above and beyond that, it's going directly against how the carseat manufacturer has tested the carseat. In short, if the carseat failed in a collision, the manufacturer would have no liability for the injury because the seat was being blatantly misused.
The law in AB is 20lbs, but we have a proper use law which ends up making it 1yr and either 20 or 22lbs depending on what type of seat is purchased. It's important to keep in mind that the law is a bare minimum and not what is going to offer the best protection to a child. Children's spinal columns don't finish fusing until between the ages of 3 and 6. Until then, the spinal column - ie the vertabrae and the spaces between the vertabrae, can stretch further than the spinal cord. Worst case scenario is a young ff'ing child suffers a broken spinal cord and dies instantly. Less than a year ago in the city here (Edmonton,) we had an 18mo old child who died as a direct result of a collision where his primary injury was a broken spinal cord. The child was kept alive on life support for awhile, but eventually removed from life support.
It's a very delicate subject to bring up, even with me being a technician, I still had difficulty with my bro/SIL and my own nephew who they moved him ff'ing at 7mos. He met the weight limit, but not the age or height minimums to ff. I turned the seat back rf'ing for them, and then emailed them some links including the rf'ing video from youtube -
http://www.youtube.com/watch?v=psmUWg7QrC8. I then told them that I was giving them the info because I wanted my nephew to be as safe as possible in the car and didn't want to see anything bad to happen to him. I also promised I wouldn't mention it again - just so that it didn't become a big issue.
I would definitely provide the information, how to approach it may be difficult depending on what your relationship is like right now, but when it's something so absolutely dangerous, something needs to be said. Best of luck.