I would counter that the only way to maintain a track is by crabbing. I
think we confuse the role of the slip. In order to track straight down
the runway in a crosswind, we must adjust the direction of the glider
so the sin of the angle equals the crosswind component. This is
accomplished by turning, our yaw string ultimatley revealing our path
through the air. If you recover from your side slip, you will point at
that angle while continuing to track down the runway. Side slip,
recover, side slip, recover. The side slip has nothing to do with your
direction... it simply changes your heading so you can land with the
wheels straight.

And thus my quibble with calling crabs and side slips additive.

The advantage of using a side slip for alignment is that it reduces
variables: once the slip is established, the pilot uses the controls as
normal (or very nearly so).

My intent here is not to discern which approach is better... to me they
are pretty much the same... with preference for when the alignment
correction is made... early on final or just before touchdown. Instead,
I want to point out that there are some published, formal notions that
appear at least to cause confusion and at worst are simply WRONG.

Someone come to the defense of the sages of sport, the authors of the
Soaring Flight Manual!! How are a crab and side slip additive?