OK- nobody really gave a decent description of the lift pins, so I will give it a try.

Your wings are held together inside the fuselage by large composite spars, either with an interlocking fork and tongue and dual main spar pins (like Schleicher) which carry the load of the glider in flight, or a fore/aft spar arrangement with one main pin, generally located at the center of the spar junction, in the middle of the fuselage. The carry-through load is handled by pins extending through the ends of the spar stub that fit into sockets at the root of each wing. This is a characteristic of Schempp-Hirth gliders..

Both design methods have been utilized by other manufacturers. Interestingly, Jonker Sailplanes use the two main pin configuration on the JS-1, while the single pin and lateral spar pin/socket design is used on the new JS-3.

Now, the lift pins. Since the main spar is designed to carry the load of the aircraft laterally, there must be a way to constrain the wing and keep it in horizontal alignment with the fuselage. This is handled by the pins extending from the fuselage ahead of and behind the main spar. (Although Jonker prefers to have the pins extending from the root rib and fitting into sockets in the fuselage.)

Essentially, the lift pins keep the wing in proper alignment relative to the fuselage while in flight, while the spars and their retaining pin(s) hold the wing together and carry the load of the aircraft.