Is it safe to add ProtoIncludes to an abstract class in Protobuf-net, after the datamodel has already been deployed?

Question

I'm trying to make a data model extensible after deployment. Is the following acceptable:

[ProtoContract]
[ProtoInclude(1, typeof(ProtoObject<float>))]
[ProtoInclude(2, typeof(ProtoObject<int>))]
[ProtoInclude(3, typeof(ProtoObject<bool>))]
[ProtoInclude(4, typeof(ProtoObject<string>))]

///CAN I ADD A NEW ProtoInclude(5, typeof(ProtoObject<NEWTYPE>))] HERE AFTER I HAVE ALREADY DEPLOYED???

public abstract class ProtoObject
{
    protected ProtoObject() { }
    public abstract object ProtoValue { get; set; }
}