|There's a smallar lay-in liner/booster specifically for the S Sandys. It doesn't hold quite as much as the snap-in for the OS or lay-in for the L Sandys (they're the same, just with or without snaps), but those would likely be a little bit long at present. If it's just for use at night, though, you could always just fold any extra length over the front; as long as it's inside the cover it's all good. That would be a little bulky for normal use, but for night, hey, a little more absorbancy. Otherwise you can always just use the smaller boosters with the larger diapers at a later point, too.