Building of Menegroth and introduction of dwarves are waiting for Season 3, as is the intro of the Green Elves to Beleriand. We can show Lúthien at that time if we don't want her birth part of 'Thingol and Melian form the realm of Doriath' in this episode. Perhaps we could end their story with an image of Melian pregnant? We are planning to just leave Middle Earth to its own devices, as there is no communication across the ocean during this time, and the lives of the Sindar are a mystery to the elves of Valinor. Events that chronologically happen 'during' Season 2 (but in Middle Earth) will be told in Season 3.
Trial of Melkor is in Episode 8, *not* Episode 7. We do not have time for that here.
This episode is to focus on the wedding of Indis and Finwë as well as the breach in the relationship between Fëanor, Fingolfin and Finarfin. Fëanor and Nerdanel can also get married in this episode.
We will be saving the birth of future kids (the children of Fëanor, Fingolfin and Finarfin) for later episodes. The introduction of, say, adult Maedhros and Fingon will definitely be waiting for a later episode (probably 9).