How to credit dancers in musicals

In an effort to give credit to professional dancers who appeared in musicals but were almost always uncredited, I have been working on adding their names to the cast lists of the films they appeared in. Films from the Hollywood studio era will not infrequently have long lists of uncredited bit/extra roles in the IMDb cast lists, but often the dancers are wholly excluded, despite having a part in the film that is much more substantial than "Party Guest" or "Audience Member". However,  when the dancers are integrated into the scenario of the film, I am unsure of what the correct Character Name to use. Existing entries are done in a variety of ways, and the guidelines do not appear to give any specific advice on this matter. 

For example, in the film The Music Man (1962), numerous dancers were employed in the film, and most of them appear in several musical numbers, as background in scenes before and after the actual dance numbers, and also as background characters in scenes without dance numbers. Ostensibly, they all represent ordinary citizens of the town and none of them represent actual dancers or performers in the context of the film. However there are numerous other performers (actors) who are not dancers and do not perform in the dance numbers, also representing ''townspeople". To complicate this, the dancers may appear as adults in one scene and students/teenagers in another scene.  Existing credits sometime use the Character Name "Dancer" and sometimes use a contextual name such as "Townsman", "Student", "High School Girl", etc. which do not distinguish the fact that they are dancers, their most salient function in the film.  To be clear, I am talking about professional dancers who appeared in numerous films as dancers and often as well on the stage, in nightclubs, etc. as professional dancers.

Another example would be in The Unsinkable Molly Brown (1964) where there is a major dance number in a saloon in mining town. All the dancers in the scene are ostensibly miners (although not every "Miner" in the scene/film is engaged as a dancer). Should these performers be listed as "Miner"? As "Dancer"? As "Miner - Dancer" or "Dancer - Miner"? As "Dancing Miner"?

I noticed for a recent title, La La Land (2016) performances of this type are listed as, for example, "Traffic Dancer - Girl #2" or "Hollywood Party Dancer - Creepy Guy" although the dancers in this film are screen-credited and perhaps that is what determined the format of the Character Name rather than any IMBb formulated standard.

Of course, some cases are simpler, when the dancer plays a dancer/performer and can straightforwardly be called "Dancer".

It seems there should be some way to give these performers their due and distinguish their function in the films, but I am not sure what the proper way to do this is, if there is one. Some authoritative advice would be very much appreciated. 

Thanks,

Glenn