My sister and I are 10 years apart. We seem to have a strange relationship. She thinks everything is fine between us, but I have questions. For instance ;she will call my daughter, who lives with me, and ask her out for coffee. If my daughter goes and I don't she'll say 'of course she could have come. I explained to her that she should say so when she asks my daughter if she wants me to go too. She doesn't and seems to expect me to invite myself, which I feel funny doing. I feel that I'm being deliberately excluded. Am I being too sensitive ?