My Husbands Grandmother just recently moved in with her daughter (my MIL) She's 80 had a few strokes (no major damage) and very lucid, Grandma and I are very close so we write letters to keep up and exchange phone call's as often as we can etc.. The problem is, I am certain that my MIL is opening the letters and reading them before she is giving them to Grandma. Is this legal? And how can I send mail to grandma securley to make sure it is given to her and her alone when they share a PO Box? Any advice would be much appreciated. P. S. The reason I am certain of MIL opening mail is phone conversations with MIL where she's bringing up private matters she know's nothing about that I've discussed with gramdma and grandma only through letters, plus this did not start happening untill grandma moved in with her, when grandma lived on her own she and I never had to worry about privacy. Grandmas friends and church family back home where she used to live are suspecting the same because when they call her my MIL starts asking them questions on topics that they wrote in letters to grandma and that grandma did not discuss with her. Thanks in advance