Question

why cam't i add some surnames without the the red dotted line under the surname.

Answer 1

I suspect that is a spell-checker. If you key in Wolf there's no red line? It appears when you add the 2nd 'f'?

Comments

it's supposed to be 2 f's.

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Just ignore it. The spell checker doesn't have all possible spellings of all possible words and names that are similar to common words but different will show the red line.

Answer 2

Without being able to see what's happening on your end, I think that red line is the standard red line that appears whenever you type something that is not a recognized English word, just like when you write documents with a word processor.

Answer 3

Depending on your browser, you may be able to add words to its dictionary.

On Firefox, I highlight the word, right click with my mouse, and see a menu with Add to Dictionary as one of the functions.

Once I add a word to my browser's dictionary, the red-dotted line no longer appears for that word.

Answer 4

The spell-checker (red dotted line under a word/name) is a feature of your browser -- not this, or any other site.