a grammar question in quenya

If tanslated ´´of my thrall´´is mólinyo. When it comes to translating´´of my thralls´´, what kind of form is properer, mólinyaron or mólinyon?

The core of question is that whether prefer putting ´´r´´ and´´on´´ together in double plural form or embody plural just in genitive not in possessive adjective´´nya adding r´´

Mólinyaron is the correct translation for plural. The plural genitive case uses both the plural marker of the noun (in this case '-r' from mólinyar) and the '-n', the plural marker of the case.