Abc
If you want it to be a diminutive of [name_f]Diana[/name_f], then you create a new origin for it, so you can decide on its pronunciation. That way it’s not associated with any language so there’s not much need to follow their rules.
You can’t do this for every name but in this case it seems fine to me.
[name_m]Just[/name_m] don’t worry about the typical pronunciation. [name_u]Or[/name_u] spell it Dya or [name_f]Daia[/name_f]
In this case, yes. Although I think of the word dire.
[name_f]Daia[/name_f] looks cool! Didn’t think of that!
In this case, I’d second this Daia looks good too
[name_f]Dia[/name_f] (dee-uh) means day in Portuguese. Your pronounciation is nice too. [name_f]Daia[/name_f] looks beautiful! What about Dya, Diah or Dyah?
In this case, absolutely, as you’re using it more as a nickname, rather than taking a name from another culture outright and refusing to acknowledge/honour the original pronunciation. It isn’t always the case - if it were say, [name_f]Caoimhe[/name_f], I’d say no, but for [name_f]Dia[/name_f] as a diminutive/shortening of [name_f]Diana[/name_f], I think it’s fine.