Seatbelt extenders are an emergency last resort option only.
What is each child's age, weight, height?
What are the exact carseats you currently have?
What year is your vehicle?
What is your budget?
LATCH is not required for installing carseats -- it was invented in hopes of being easier, but the seatbelt is perfectly fine so long as you're following both carseat + vehicle manuals! The most important thing is that each seat is
independently secure: harness seats must have less than 1" movement
at the belt path.... In general, we would prefer to have the boostered child in the center but not because of
LATCH, rather simply because safest practice means puting the least protected passenger in the safest location (boosters are not as safe as
RF harnesses). If the center has a lap only belt, then the
booster cannot be used there.