What I learned...
...it's all about doubling up the corner chains!
At first I treated each corner chain stitch as a seperate stitch, as you do when joining granny squares, but soon found my joins were not going well, I was left with overhang! After counting and recounting my stitches on the outside of the squares and finding I hadn't either missed a stitch or added one in I realised that the corner chains had to be doubled up when joining.
So how do you connect multiple small squares to the larger squares?
First you need to join your smaller squares into one piece.
Ideally you have left a tail on your work just over the length of the four sides of the square. This is just enough to join that size square.
Join two squares starting from the chain at the end of each side and working across (please see below or Attic 24).
The tail has is shown here.
To start push your hook through the corner chain.
Then push the hook through the corner chain of the square to be joined. Wrap the tail over the top of your hook. Pull the tail through the work. You now have a loop in your hook.
The next stitch is a bit fiddly and I couldn't photograph it well, your next stitch you need to go through is the tiny stitch just to the left of the hook in this photo. Wiggle your hook in and through the back square, wrap the tail round as usual and pull through. Keep going until the chain stitch at the other end of this side, join one chain stitch from each square. Pull tail through, Done!
Now to join a larger square to a number of smaller squares you have already joined together.
Again Attic 24 shows how you start in the corner at the chain stitch
closest to the side you are joining. To start the join push your hook
through the corner chain of each square, wrap joining wool round and
pull through. You now have a loop on your hook.
With a loop of joining wool, dark blue, on your hook push it through both squares you are joining, light blue and beige. Giving you three loops on the hook.
Wrap joining wool round the hook and pull through all three loops. This gives you the next loop of joining wool on your hook. Continue working along the edge remembering to jointhe outside loops.
Now to join the two smaller squares on one side to one larger on the other. In this example the larger square is the light blue on the right.
When you reach the end of the smaller beige square do a joining stitch at the top of the last dc as usual.
Now just like a normal join push your hook through the larger bright blue and through the corner chain of the beige sqaure.
Without wrapping your joining wool round go into the first corner chain of the next square to join, dark blue here. You will now have four loops on your hook, from right to left, the joining wool, the larger square and the corner chains from each of the smaller squares. Now wrap the joining wool round your hook and pull through all 4 loops.
Now continue on as before. If you don't double up the corner chains in the joining process your small squares will end up overhanging your larger square.
This method works well, last night I joined my 9th panel onto the main blanket. Not only is this a huge milestone as the blanket is now half way to being complet but I joined one edge made of 4 & 8 rounds squares to an edge of 10, 8, 6, 4 & 2 rounds squares and they matched up perfectly!