You need to check what she is serving for Christmas dinner. My DDIL always has a choice of pate or smoked salmon for starters so would be quite upset if I turned up with ss for brunch. What about American pancakes, make in advance, wrap in foil and take a selection of toppings-blueberries, maple syrup etc. Or Irish potato scones. Or if it is to be a buffet style brunch devils on horseback. Nigel Slater has some great variations on these www.theguardian.com/lifeandstyle/2011/mar/27/nigel-slater-devils-horseback-classic