99 blazer/carseat in middle

We just got a 99 4 door blazer. I was excited b/c I thought the safest place for a carseat is in the middle. My car doesn't have middle seatbelts so she was always on the passenger side. I was looking through the car manual and it said not to put carseats in the middle b/c the restraints wont work right. It is a 60/40 bench seat. Do I need to put her behind my seat. She is in a fwd facing alpha omega. What about when I have another baby. Would the infant seat be unsafe as well. I read and re read the book. It goes into no detail. It simply shows a pic of the seat in the middle with a / through it and says the restraints wont work proprely.
Is this because the manual is older and things have changed? Is it b/c the tethers are on the side? I put it to the side and it isn't as tight as it is in the middle?
What shoul I do?

[UlrikeDG]

Unfortunately, no child restraint can go in that position, and if there is no shoulder belt there, it isn't a safe location for an adult passenger, either. I believe that the problem is that the seatbelt anchors are too close together to correctly hold a child seat. What a frustrating thing to discover after making the purchase!

We have a 2002 Bravada-same thing as a blazer-with that same restriction. The strangest thing is the tether anchor behind all three seats. Why have a tether anchor if you can't have a car seat in this position?? Talk about misleading!