not an expert here, but I have multipoint locks on my Andersen patio doors. Mine were purchased as a set. One side has a thumb turn and one does not. When you pull the handle up on the door the top and bottom bolts slide into place and the thumb turn throws the deadbolt at the handle. It is not locked if you only lift the handle - the thumb turn keeps it all in the locked position. Hope that makes sense.

Thanks! Does the exterior knob rotate on your side without a thumbturn?

Rocky Mountain offers a set with a key (Entry), a set with a thumbturn & plain outside (Patio), a set that's just passage and a dummy set.

It seems that I might need sets both with thumbturns for each door?

no, just on thumbturn. Lift the handle on the door without the thumb turn to set the top and bottom bolts, then set the door with the tumbturn by raising its lever, turn the thumb turn and that turns the deadbolt that locks the two doors together. All multipoint doors have levers on both the inside and the outside - the levers on each door will raise at the same time when you set it - no knobs. It looks like you want the patio set.