How can I add, edit or delete an existing deepL Glossary using C#?

Question

I want to use the deepL API in a C# project. I want to translate from one into 3 different languages and work with a single glossary for each language pair. However - a glossary is not static and from time to time it needs to be updated - e.g. by extending it by a new word pair or replacing or deleting an old one.

In the deepL API documentation @gitHub I find only methods to create or delete a glossary completely:

// Create an English to German glossary with two terms:
   var entriesDictionary = new Dictionary<string, string>{{"artist", "Maler"}, {"prize",   "Gewinn"}};
   var glossaryEnToDe = await translator.CreateGlossaryAsync("My glossary", "EN", "DE",
   new GlossaryEntries(entriesDictionary));

After that I can get the glossary ID and work with it referencing the glossary by its ID. But I don't find a method of how to extend and update the glossary once it was created. Let's say I want to add the new pair {"age", "Alter"} - How can I add it to the existing glossary? Besides that I want to check if there is already an entry for "age" and then replace the pairing by the new one. A possibility to delete existing entries would also be necessary.

The only solution I found so far would be to export the whole glossary, do the described actions on the exported list, then delete the original glossary and create a new one. But that seems to be ridiculous - and I would end up with a new glossary ID every time.