This discussion get me the idea. The possibility to use the single copy of the episode in different places. For example, serialized specials. We have them as separate series now, but we could also have them listed in their parent series without creating a duplicates. So the links would lead to the same episode pages.
I'm not sure, maybe it fits in this pending feature http://www.tvmaze.com/threads/136/relations-between-shows (the part about relations between episodes).
Taking your example, Simpons may not be a seperate entry as series in our database, therefore it should be rejected when it is requested. It is part of it's original show and would be impossible for us to check on it.
The pending feature about relations between shows has more to do with overlapsing series, which become more frequently. For example the Marvel and DC's series or a series which is a remake of another series.
So what does "Consider relations between episodes as well?" mean? Crossovers?
While this maybe not such a good idea for Simpsons, this could really work for the actual specials, which are the part of some show, but the policy dictates to have them as separate show.
It would most likely only be valid for crossovers indeed or something similar to that, however to create a non-existing series (according to network) is not going to happen, no matter if certain people are only interested in certain parts of a specific show. On top of that It would be impossible to verify and check it as tons of shows have different segments within their episodes.
