I'm fairly new to genealogical research. I have a bunch of stuff that I want to organize and be able to track, so I started looking at numbering systems. I think I have settled on a mix of Ahnentafel and Henry systems, but as I was numbering people, I came across a problem. I have twin nieces (my brother's children). So, I numbered them 1.31a and 1.31b (my brother is 1.3). Does this make sense?