I took a strip of cloth that goes around the body of the teddy bear, measured out where the arms would come in and just slit it at that point. Slide the arms in, wrap it around the back, a few stitches to hold it down in place (or a good glue to stick it all down?!) and you’re done.
For the pink bears, I used a lace, and did a row of running stitch along one side of the lace – the pulled that running stitch to get gathers before measuring out where it would fit our little teddies.
The orange bustier is again another lace which is cut and then held together with a chain of crochet and tied around the back. I did sew the bustier on to the teddy (so it’s not removable – and also safer for kids)