I have a frequent guest who has something of a weight problem and gets up from chairs by leveraging herself on one corner of the back. As a result my chairs tend to develop problems - specifically the bracing separates from the main supports. In the past I have tried to fix these by separating them a bit more, adding glue, and then clamping them together as tightly as possible. This works for some time, but over time the problem recurs. This last weekend one of the chairs cracked - see photos.
I don't want to drill holes from the outside of the chairs to put fasteners through the legs and I can't disinvite her. So, can someone please tell me how to fix these chairs ( we have four of them) so this stops happening?