:thinking: You could either pick up and knit on two opposite sides and then do it again on the other two sides--the second two sides would include the added on edges of the first two sides. Not as pretty as mitered corners, but easier.
For mitered, I've read that you increase one stitch on each right side row in the stitch before the corner stitch.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry