Exporting site and address data
It seems the only two unique things about the blocks of code are the Tables that you are searching/adding to and how the SITE_IDs are obtained (from different types).  You could just make your method accept two additional parameters, the table that is being searched and a lambda which selects the SITE_ID.  You'll just have to rewrite some expressions.

public static void ExportData&lt;TEntity, TSite&gt;(
    ObjectSet&lt;TEntity&gt; table,
    Expression&lt;Func&lt;TEntity, TSite&gt;&gt; siteIdSelector,
    TEntity data)
    where TEntity : class
{
    var condition = GetCondition(siteIdSelector, data);
    var isInTable = table.Where(condition).Any();
    if (!isInTable)
    {
        table.AddObject(data);
        table.Context.SaveChanges();
    }
}

private static Expression&lt;Func&lt;TEntity, bool&gt;&gt; GetCondition&lt;TEntity, TKey&gt;(
    Expression&lt;Func&lt;TEntity, TKey&gt;&gt; keySelector,
    TEntity data)
    where TEntity : class
{
    var entity = Expression.Parameter(typeof(TEntity), "entity");
    var entityKey = BindParameter(keySelector, entity);
    var dataKey = BindParameter(keySelector, Expression.Constant(data));
    var body = Expression.Equal(entityKey , dataKey);
    return Expression.Lambda&lt;Func&lt;TEntity, bool&gt;&gt;(body, entity);
}

private static Expression BindParameter&lt;TEntity, TKey&gt;(
    Expression&lt;Func&lt;TEntity, TKey&gt;&gt; keySelector,
    Expression entity)
    where TEntity : class
{
    return new SubstitutionVisitor
    {
        OldExpr = keySelector.Parameters.Single(),
        NewExpr = entity,
    }.Visit(keySelector.Body);
}

public class SubstitutionVisitor : ExpressionVisitor
{
    public Expression OldExpr { get; set; }
    public Expression NewExpr { get; set; }

    public override Expression Visit(Expression node)
    {
        return (node == OldExpr) ? NewExpr : base.Visit(node);
    }
}


Then to use it, you could do something like this:

ExportData(_context.FLEX_INV_EXP_SITE, entity =&gt; entity.SITE_ID, siteData);
ExportData(_context.FLEX_INV_EXP_ADDRESS, entity =&gt; entity.SITE_ID, addressData);