Need help with a dirigible plumb pillow

[Ninani]

Hi I am working on a dirigible plumb pillow from the Harry Potter crochet book and I am stumped as to how to do this. The pattern says and I quote, “double crochet in the next three stitches(switch to b on last yarn over) bobble stitch (switch to c on last yarn over), single crochet 4 together between each section of previously worked bobble stitch, (switch to a on last yarn over) 

how am I supposed to sc4tog and how am I supposed to make it so that they don’t add any more stitches to the rows

[Granny Square]

I'm defining a partial stitch as any plain/basic stitch (SC, DC, etc.), just short of the last yarn over and pull thru.  This leaves the loop that is 'always' on the hook, and the last loop of that stitch, on the hook.

Each partial stitch made adds a loop on your hook.  So when this is in process, there is always 1 more loop on your hook, than there are stitches.

So for SC, you have 1 loop on your hook from before you encountered the sc4tog.  Insert your hook into the first stitch and pull up a loop--there are 2 loops on your hook. Insert your hook into the next stitch, and pull up a loop - there are now 3 loops on your hook.  Repeat this twice more, and you should have 4 partial scs made into your fabric, and 5 loops on your hook - yarn over and pull thru those 5 loops.  I have to admit I can't recall doing this for SC for so many stitches, so it might be a little hard to wrangle because the stitches are so short.  

And, this won't be adding stitches, this is a 3 stitch decrease - any 'together' instruction is turning some number of stitches into 1, so after this you will no longer have 4 stitches, but 1.  

[Granny Square]

Here is a youtube showing sc4tog, sometimes a picture is worth 1000 words