How to add new type inside existing index using Nest?

I am using Nest to commuicate with ElasticSearch indexes.

Now, I am trying to add new type inside existing index :

    if (elasticClient.IndexExists("catalogindex").Exists)
        {
            var request = new TypeExistsRequest("catalogindex", "product");
            if (!elasticClient.TypeExists(request).Exists)
            {
               //here I want to add the mapping for my product type
            }
        }

So Is there any method I can use to do that?

P.S

I know that there is CreateIndex() method but what if I want to add new type to that index without recreating the whole index.