I think I'm going to have to see if I can get my hands on the actual record for the marriage between Sarah and Ralph. I can't see any other way to shed light on this.
As far as I can see, Ralph is in the 1891 census. He appears to be boarding. So, the marriage took place while he was living. There's no sign of his daughter, Mary J.
I keep hoping that I'll just find that there's another Sarah Rice and that I have the wrong Armstrongs. I suppose it's possible, though not likely.
This situation is very interesting. I now have a possible explanation for why my grandmother had no idea that she was half English, which I discovered when I started doing my tree. She believed that she was 100% Scottish. It's very likely that this side of the family was closemouthed to hide its secrets.
I'm still looking into this. I have yet to find anything that I haven't indicated here. If anyone has any thoughts or info, I'm all ears.