The question to be asked is: How do we deal with these Stations? It is all a matter of context. In the context of the HeroQuest, each Station has a single purpose and a simplified story with a particular benefit or result. In the context of the full HeroQuest of the Station, there is a lot more detail involved with Stations and abilities used, gained and lost and a far more detailed story. Such detail would only confuse an umbrella HeroQuest and is simply incidental. Also, anyone performing the umbrella Quest would not want to be bogged down in the individual detail of the Stations.
Where a sub-Quest grants an ability or power as its major goal it will still grant that ability or power as a Station albeit in a reduced form. One example of this is the Shield of Arran Quest. This is a Station on both the Wooing of Ernalda Quest and the Arming of Orlanth Quest and as a Station it allows the Questor to sacrifice for the Great Parry spell and to use the Great Parry spell Heroically. As a HeroQuest it allows the Questor to sacrifice for the Great Parry spell, use the Great Parry spell Heroically and also to join the Shield of Arran sub-cult of Orlanth.
Sometimes a HeroQuest may result in the gaining of a geas that is not gained from the Station form of the HeroQuest. So, in the Shield of Arran Quest, Orlanth gains the geas "Protect Earth Priestesses" but in the Shield of Arran Station he does not gain this geas.
A Station may be Invoked to have a certain effect without side effects whereas Invoking a full HeroQuest may result in side effects that are undesirable. Often HeroQuestors will learn a full HeroQuest and also learn the Quest as a Station on another Quest so that they can Invoke the simpler version without the extra baggage.
When performing a known HeroQuest as a Station, an experienced HeroQuestor may be able to modify the Station slightly using his knowledge of the full version of the HeroQuest and modifying this to affect the Station. This is a tool used by powerful HeroQuestors who know many different versions of HeroQuests and is not something to be done lightly.
In a very real way, this article is a reflection of the game mechanics of HeroQuesting rather than the actual state of affairs. In Glorantha, I do not think that there is a distinction between HeroQuests and Stations, they are all treated the same. However, there is a real world analogy that should illustrate the problem. A book on the 20th Century would probably have a chapter devoted to the Second World War but may only mention the Siege of Stalingrad, Dunkirk Evacuation and Normandy Landings in single paragraphs. There are books that cover each of these events in greater detail and each of these books would contain descriptions of those events and the events that make them up. There are even more books that cover particular portions of these events in even greater detail. Which of these is correct? The answer, of course, is - All of them, but in the context of the 20th Century the Second World War is important but the Siege of Stalingrad is not so important, even though it is important to the Second World War and the people of Russia and Germany.
I hope that this has not confused anyone and gives an idea of how to incorporate HeroQuests as Stations in other Quests and also how to expand Stations into full HeroQuests in their own right.