I have an infant seat in the side position (uses the lower anchor point) and a convertible car seat facing forward in the middle (uses seat belt, no lower anchor points). Works great, as we leave the rear seats flat 90% of the time so the stroller is easy to put in/take out, and still lets an adult sit in the middle row side seat comfortably.
Do note that the lower anchors are only on the middle row side seats, and both rear seats. The middle row middle seat is more narrow than any other seat, so when you slide the side seat forward to let someone into the rear, it does press against the side of the convertible car seat and pushes it over an inch or so. Nothing major, but noticeable.