"Pwy ydy hi?"
Translation:Who is she?
Really? I thought the pronoun 'dy' - 'your' is the genitive/ possessive case for 'you' and 'fy' is 'my' also in genitive case?
I wouldn't consider the possessive determiners to be a case form of the pronoun but instead a related word.
German, for example, has separate possessive determiners and genitive case forms of pronouns (sein Haus but wir gedenken seiner).
Or Slovak which has bezo mňa "without me" (bez(o) takes the genitive case) but môj dom "my house".
But how Can 'Fy' not be in a possessive case or a genitive case? It's only function is to be a first person pronoun that indicates possession. What exactly disqualifies it from being an inflected form of the word 'fi'?