for a special reader with a problem granny square: I know you were waiting for a post so I thought I would do one for you! Hope this helps a bit.
I enquired in my facebook crochet group for you re the buckling of your granny square blanket. Other then them saying to use same amount ply, same hook, and even tension, they haven't had a problem. Another suggestion is to decrease your corners eg instead of doing [3tr 2ch 3tr] in each corner try doing (2tr 2ch 2tr) and see if that helps.
If there are any readers that can help with another suggestion, feel free to leave your comments!