I finally got around to fleshing out the other NPCs your PCs are about to meet in Aceron Manor. I'm going to start crafting my reply now, but it definitely won't go up until tomorrow.
Knowledge checks might help identify the dinner guests, although they all look like they come from beyond Bluffside (so the DC are high [25+]).
However, you already know that Lady Heather Devereux comes from Jurral and that her father is a high-up member of the Gardes Rouges of Coeurdî. Even without a Knowledge check, the Exemplars have heard of Coeurdî simple through the constant gossip of the city's streets. Coeurdî is an island kingdom and Jurral is its capital city.
Anyone with Knowledge (nobility and royalty) has a +2 circumstance bonus to know more about Lady Heather and her father.
Lady Talitha's six guests look as if they are either nobles or rich merchants. Beyond Lady Heather and her father, there are two human men, a half-elf woman (standing next to one of the men), and a dwarf that dresses in masculine attire but wears intricate jewelry and has a more feminine hairstyle (but with long sideburns). The dwarf has many visible piercings that are made from silver and some sort of blue stone.
More details in my post tomorrow.