The last ewe still hasn't lambed, but one of the goats stepped up to fill the birthing gap -
The above photo is seconds after I discovered them inside the goat house, so you're seeing exactly what I saw (minus my jaw hanging open, obviously). I had zero idea that she was pregnant. We don't keep any bucks, nor do our nearest neighbours. There was a ram in with her but shoats (sheep/goat hybrids) are too rare to be a possibility. If I do the maths, she was covered in late November last year, just before I took her son away. The kids, both does, have Boer goat markings like him.
So far the kids seem healthy, despite having a brother for a father. I think the saying goes "If it works, it's line breeding and if it doesn't, it's inbreeding". Then you eat your mistakes and try again.