I won’t ask dang to remove it from the post, because that would actually make this conversation seem out of place, but I doubt that I’ll use the term in the future. Won’t be the first anachronistic term I’ve stopped using.

Not a big deal. I can always work to modify awkward habits.

Sorry if I my comment made you you feel uncomfortable. I see no evidence that any red headed stepchildren or their parents have been offended here. I just always feel when I hear this phrase, that as someone with a vested interest I should give the red step children a shout out.

Not a problem. I am always glad to see alternative perspectives.

Give my regards to your dear Ginger. I'm married to one.

I see no evidence that any red headed stepchildren, their parents or their spouses have been offended here.

Odd one out? Even difficult child? beyond that I’m not sure as I think it’s meaning can change from person to person. Key takeaway is just don’t use that term.

Got me thinking about that too and doing some googling I didn’t find anything that fits perfectly into what OP wanted to express. I suppose it’s best to rephrase it entirely.