I don't believe AM "lost it" that evening over something his son said, as suggested by a "talking head." It doesn't explain the blue raincoat. It doesn't explain how he was able to shoot his son, then rapidly grab a shotgun to fire at a running Maggie. She was shot 5 times, including in her leg. He wanted to take her down, then while she was positioned on one knee with her head leaning forward, he shot her in the head with a fatal blow. Deja Vu with BarryMorphew chasing Suzanne around the exterior of their home with a dart gun.
However, I agree with you in that the victims were served their final meal at their favorite Hunting Lodge. I could hear the glee in Maggie's voice when she said, "It's a guinea!" Up and until they were killed, I think AM wanted them to have one last fun experience at their beloved Moselle. AM enjoyed a final hour or two with Paul as we heard them laughing over the tree.
Other than BarryMorphew, I've probably never detested a male killer as much as I do AlexMur-dock. Dock, as the Judge told the courtroom today. He deserves the Firing Squad if found guilty of their murders.
All MHOO