C# code merging with enums with slight differences
<p>I have to merge C# codes from two similar solutions but I have some issue with enums.
The projects use <strong>.net2.0 and I have to use it as well</strong>.
The projects have some common class that contains enum with the same name but some difference:</p>

<pre><code>using System;
using System.Collections.Generic;
using System.Text;
using System.Net;

namespace MyProject
{
    public enum LETTERS
    {
        non = 0,
        a = 1,
        b = 2,
        c = 3
    }

    public class MyClass
    {
    public int v = 0;
    .
    .
    .
    public LETTERS lt = 0; // my enum
     }
}
</code></pre>

<p>There are also many other uses of this "enum" like:</p>

<pre><code>tmpChild.Type == typeof(LETTERS);

this._data.LTR = (LETTERS)valueListUpDown_LTS.Value;

AddData(new SFunc(0,typeof(LETTERS), LETTERS.A));

LETTERS letters = LETTERS.a;
</code></pre>

<p>The second project is identical  but the enum looks like this:</p>

<pre><code>    public enum LETTERS
    {        
        a = 0,
        b = 1,
        c = 2
    }
</code></pre>

<p>There are many various uses of these enums in the code and the code has many projects that use this assembly as a refference.
I would like to know what is the best way to merge those solutions.
I think about a method that returns enum type according to string but don't know how to implement or use the returned type in all cases.</p>

<p>Please Advice</p>

<p>---------- Edit ----------</p>

<p>Some other constraints that I have are:</p>

<p>I can't use nullable type or change the enums values (i can change their names)
because in some cases there are serializers that write and read it to\from a file.</p>

<p>I think of using a method like this:</p>

<pre><code>        public static Type LETTERS(string letters_type)
        {
            if (letters_type == "type_a")
                return typeof(LETTERS);
            return typeof(LETTERS_B);
    }
</code></pre>

<p>But don't know how to cast and use a Type as enum in each case
At runtime I know which version of enum I should use, that's why such method can help.</p>

<p>Thanks</p>