Multiple Inheritance using XmlAttribute element?

I have a class and inheritance like this in my deserializable class file as shown below. I want to create another class called VendorBase which has Xml attribute called Vendor. I want my Customer class to inherit that as well. How can i achieve it?

public class Customer : CustomerBase
{
    [XmlAttribute(AttributeName = "Customer")]
    public string Customer { get; set; }

    [XmlAttribute(AttributeName = "FieldValue")]
    public string FieldValue { get; set; }

}

public class VendorBase
{
    [XmlAttribute(AttributeName = "Vendor")]
    public string Vendor { get; set; }
}