I think you'll see amazing results if you keep a jar full of 'real' dog treats right by the door. And when you allow someone in, you hand over some of these treats (NOT dry milk bones ! but wet yummy stuff like cheese or moist yummy things) to the friend and have they initially just hold it in their open palm (so they come in low under the dogs face, less threatening, like feeding a horse) and the dog comes in.
Once the dog gets that 100% of the people coming in the house have CHEESE/CHICKEN/BEEF just for him, the fear should be ebbing and then you can start having them ask him to 'sit' or 'down' and give the treat for a specific good behavior and not just the NON fear behaviors.
MACH3 Bretta Lee Wildhaus MXG MJG MXF MFB TQX HIT CGC TC
Glory B Wildhaus AX, AXJ, XF
"How is it one careless match can start a forest fire, but it takes a whole box to start a campfire?." ANONYMOUS