Three months ago H and I visited 2 x SD (32 and 34) who live in another city for a weekend.  We then took them, SD1 has a H and son, SD2 is divorced and has no children, to a beautiful holiday home in a gorgeous part of NZ for three nights.  My two biological sons flew into the town and joined us as well.  We paid for everything, which we are both happy to do.  However, can someone tell me why youngest SD makes sure she thanks her father and not me, when I am not present?