Per Dickey, “τῶν (τῶν) νεανίων δούλων” is an impossible construction. But what would be a legit way to render the meaning of “of the young men’s slaves”? Dickey does not explain it here.Thanks in advance.
τῶν δούλων τῶν νεανιῶν
If I got Dickey right, this won’t do either. At the very least, it is ambiguous: who possesses whom?
ἡ δούλη ἐστὶν ἡ μήτηρ τῶν δούλῶν τῶν νεανιῶν. καὶ αὕτη ἐστὶν ἡ μάμμη τῶν νεανιῶν τῶν δούλων. καλὴ δὲ μάμμη ἐστὶ τῶν τῶν τῶν νεανιῶν δούλων νεανιῶν.
“One genitive can nest within another but not if they have articles of identical form.” (Dickey, 17) The respective constructions of your first two sentences, if I got them right, are not possessives.
"ALMOST EVERY RULE PRESENTED IN THIS BOOK HAS EXCEPTIONS, MOST OF WHICH ARE NOT MENTIONED. (Dickey, 1) 
Try telling that to my mother. 
- I am asking about the rule (i.e., regular ways to express such meaning), not about exceptions.
- As for exceptions, I’d prefer them to come from native speakers; otherwise I cannot tell exceptions from mistakes.
As I said, I think this would be τῶν δούλων τῶν νεανιῶν. Context would eliminate the ambiguity except when it would not.
In my view, this translates as: The slave [woman] is the mother of the slaves, [namely,] of the young ones.
Sure, depending on the context, it could mean this.
I think you’re right: in the nominative, “the young men’s slaves” would be οι δουλοι οι των νεανιων (or, οι των νεανιων δουλοι, but that’s not relevant here). If we change that into genitive, we can’t just drop the second οι.
Where did the last τῶν come from?
I don’t have the book in front of me just now, but I believe that in the exercise key, she gives examples of the alternate form.
From my carelessness 
Thanks, will correct in the posting.
No, for the “the young men’s slaves (gen.)” (p. 18), she just says in the Answer Key (p. 217): “not translatable this way because it would require two identical articles in succession.” She does not say which way it is translatable. Hence my question. (She might be saying it further in the book but am more curious than I am patient.)
I would then rephrase my question thus: Is there a way in Greek (like it is in English) to phrase it so that it would mean “of the young men’s slaves” in every (=regardless of the) context?
ἔκλεψα τὰ ποτήρια τῶν δούλων οἳ δουλεύουσι τοῖς νεανίαις.
St. Paul uses a number of successive genitive constructions in the opening of his letter to the Romans, and they never look ambiguous to me. So I think that Markos is correct.
If you are looking for other ways to say it, I suppose that you could say τῶν δούλων οὓς ἔχουσι οἱ νεανίαι. Or τῶν τοῖς νεανίαις δούλων. Or τῶν παρὰ τοῖς νεανίαις δουλευόντων.
EDIT: Or the example that Markos posted above while I was typing this.
How is this relevant? I cited exactly what Dickey says (on p. 17): “One genitive can nest within another but not if they have articles of identical form.” (Dickey, 17) I do not see this in the opening of the letter to the Romans. But thanks for suggesting alternative constructions. They remind me of the current tendency in German to avoid the genitive: “Der Dativ is dem Genitiv sein Tod.”
It will be more profitable not to pursue this (and not to pay much heed to the posted suggestions, some of which are bad) but just to continue with the book. If you must have an answer, take Markos’ first one (but ignore his follow-ups). No-one would take that as meaning “of the slaves’ young men.”
Sure. But if we had “sons” instead of “young men” it would be different. What about
? It looks like a universal solution, applicable to all cases. Isn’t it?