In Immersive Intelligence, there's a multiblock called electrolyzer and the middle shape of it is one of the shape that can form one of IW multiblock, so maybe if you can add something to detect if there are others block nearby and if the block meets the requirement it doesn't form IW multiblock but II multiblock electrolyzer.

I wasn't able to replicate this. The electrolyzer forms just fine and also the isolated middle shape is not a valid mechanical multiblock structure.