How do I continue to stay on my diet program with relatives in town?

My mum has had this dilemma for the past 10 years. It really comes down to your own priorities. Do you so badly want to lose the weight you can’t think of anything else, or you just trying to slim down to look and feel better? You need to ask yourself what is more important, enjoying good times with your family or fitting into a size smaller jeans. If your weight is not seriously affecting your health (including your mental health), then maybe just enjoy yourself.
Having said that I wouldn’t go to the extreme, good meals come and go, how often do you regret NOT eating something more than a day later. The Weight Watchers is a great program from what I’ve seen, it really gives you knowledge about what you consume and they even give you handy hints about eating out. Use this info, read the menu carefully and look for the healthier options, skip a starter or have an entree for your main. You shouldn’t have to suffer because your dieting, just be more aware of what you eat.