How do I present a word ending in “‑f ” that may be plural or singular?
I've typically seen this done by maintaining the format and leaving the reader to make the appropriate change in pronunciation.
- self(s)
- dwarf(s)
There may be a better way, but I haven't seen it in usage and this is certainly easy to program for if that's what you happen to be doing. The change is not particularly difficult to make for a native speaking reader, and even for non-natives the other alternatives are likely to be more confusing.