Is there such a rule, or is it something which is decided each time based on context ? Or maybe even on which type-5 noun suffix is actually used ? Because in Aurelie's example we have a {-vaD}, while in mine we have a {-Daq}.

With -Daq, you can have things within things. You can have both things be locative but not equal. Not so with -vaD: every beneficiary is individual. You could probably make -vo' work like -Daq.

There is no rule here. We have scant evidence—Voragh has given some—so I'm going on what seems natural to me given both my native English bias and my knowledge of Klingon.

If you need a rule of thumb, then mine is this: if multiple noun phrases occupy the same syntactic role in a single sentence and are equal in their scopes, they should be followed by a conjunction, otherwise they must be interpreted in some other way. Other interpretations commonly include apposition or some being subordinate in scope to others.

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SuStel
http://trimboli.name