My BFF (a tech) has a 95 Olds wagon and my MIL has an 88. You can get two tether anchors retrofitted for the second row, but you can only use them with the 3rd row seat folded. In order to install them, the center anchors for the 3rd row seat belts are undone and the bracket is added to the bolt so that it sticks up above the floorboards with the seat folded. The anchors are offset and be used with a seat center or outboard, but not center and outboard at the same time. If you need to tether 3 seats in the 2nd row simultaneously, you can feed the male end of the 3rd row seat belt up through the gap in the 3rd row seat belt and tether the center seat to that.
Your 3rd row is basically useless from a safety standpoint because it has lap belts only, you can't install a car seat, and because the seat back is so low. Anyone sitting there that is old enough not to need a car seat would be tall enough that their head would snap back over the top of the seat in a frontal crash and cause very serious neck injuries. The seat belts are handy for use as cargo tie downs if you are moving a potted plant of something you don't want to tip over, but that's about it.
One other head's up about this vehicle...kids tend not to fit in the adult seat belt properly until they are over 5 feet tall.