I switched role name "Xiao Laner" to "Lan-Er [as child]", since nobody calls her "Xiao" which only express she is the small (child) "Laner" (It doesn't feel Chinese written like that) but my personal stalker switched it to "Laner (child)" within seconds, whats so wrong with "as" ?
I changed role "Yin Yangren" to "Yin-Yang Man" because its not familyname Yin, first name "Yang-Ren" oder "Yangren" which was deleted within minutes... I changed "Lan Dong" to "Lan Long" (Lazy dragon) which did pass through.. Now I won't add the japanese role name of Sawada Kenya, since my friend might change it back again... BTW: Ma Guafu is not the name, but Guafu is widow, so it means widow Ma!!

I would suggest to write "Laner" in pinyin -> Lan'er
Maybe "er" is not really a name either, but a way to address one's child (in case of the 兒 "er"). Not that I would definitely know that, but I've got that impression in the recent years. If my feeling is right, writing "er" wouldn't be different from writing "Xiao". I agree that Xiao often means just small, even though it can as well be a name. It reminds me of that 阿/Ah thing, english subtitles sometimes write it, sometimes not.

The use of an apostrophe or hyphen is not part of pinyin orthography (which is what is used here), unless it is required to remove ambiguity.

That said, I agree with you Chen - it does get used colloquially in cases like this, so Lan'er would be fine and less ambiguous. But Laner is OK too. Lan-Er would be incorrect. The Wade-Giles mandarin romanization uses hyphens, but pinyin does not.

As for the matter of data being changed, I think we need to have a separate discussion - I will contact you separately in private.