ExpressionCombiner

public static class ExpressionCombiner
{
    public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> leftExpr, Expression<Func<T, bool>> rightExpr)
    {
        return Join(leftExpr, rightExpr, Expression.And);
    }

    public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> leftExpr, Expression<Func<T, bool>> rightExpr)
    {
        return Join(leftExpr, rightExpr, Expression.Or);
    }

    public static Expression<Func<T, bool>> Join<T>(Expression<Func<T, bool>> leftExpr, Expression<Func<T, bool>> rightExpr,
        Func<Expression, Expression, BinaryExpression> joinFunc)
    {
        if (leftExpr == null)
            throw new NullReferenceException(nameof(leftExpr));
        if (rightExpr == null)
            throw new NullReferenceException(nameof(rightExpr));

        var visitor = new ParameterUpdateVisitor(rightExpr.Parameters.First(), leftExpr.Parameters.First());
        rightExpr = visitor.Visit(rightExpr) as Expression<Func<T, bool>>;
        var binExp = joinFunc(leftExpr.Body, rightExpr.Body);
        return Expression.Lambda<Func<T, bool>>(binExp, rightExpr.Parameters);
    }

    class ParameterUpdateVisitor : ExpressionVisitor
    {
        private readonly ParameterExpression _oldParameter;
        private readonly ParameterExpression _newParameter;

        public ParameterUpdateVisitor(ParameterExpression oldParameter, ParameterExpression newParameter)
        {
            _oldParameter = oldParameter;
            _newParameter = newParameter;
        }

        protected override Expression VisitParameter(ParameterExpression node)
        {
            if (object.ReferenceEquals(node, _oldParameter))
                return _newParameter;

            return base.VisitParameter(node);
        }
    }
}