using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Globalization;
 
public class Test
{
	public static string Replacer(Match m, TextInfo ti) {
		if (m.Groups[2].Success) { // the word to be lowercased is matched
		    if (!m.Groups[1].Success) { // if it is not at the start of a string
		        return m.Groups[2].Value.ToLower();  // lowercase
		    } else {
		    	return  ti.ToTitleCase(m.Groups[2].Value);
		    }
		} else if (m.Groups[3].Success) { // abc'n matched
		    return $"{ti.ToTitleCase(m.Groups[3].Value)}'{m.Groups[4].Value.ToLower()}";
		} else if (m.Groups[5].Success) { // n'abc matched
		    return $"{m.Groups[5].Value.ToLower()}'{ti.ToTitleCase(m.Groups[6].Value)}";
		}
		return m.Value;
	}
 
	public static void Main()
	{
		var strings = new List<string> { "Van Den Broek", "Derksen-van 't schip", "In Het Lid-Van De Boer",
		"van den Broek", "Derksen-Van 'T Schip", "In het Lid-Van De Boer", "'T Gilde", "Cramen-L'amie",
		"Van den L'isle", "Jansen-D'ancona", "Ebboubola N'na"};
		// van den Broek => Van den Broek, Derksen-Van 'T Schip => Derksen-van 't Schip In het Lid-Van De Boer => In het lid-van de boer, 'T Gilde => 't Gilde, Cramen-L'amie => Cramen-l'Amie, Van den L'isle => Van den l'Isle, Jansen-D'ancona => Jansen-d'Ancona Ebboubola N'na => Eboubola n'Na
		var textInfo = new CultureInfo("en-US", false).TextInfo;
		var p = @"(?:(^)|\b)(van|de[rn]?|In|het)\b|(\p{L}*)'(\p{L})\b|\b(\p{L})'(\p{L}*)";
    	var pattern = new Regex(p, RegexOptions.Compiled|RegexOptions.IgnoreCase);
        foreach (var s in strings)
        	Console.WriteLine(pattern.Replace(s, m => Replacer(m, textInfo)));
	}
}

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