The crossover has begun! And you can read it here!

7596062
I always liked gen1’s (and even gen3’s) muzzles better

just read the comic

are are they saying g1 is cannon?! cause if those two are the grandchildren of who i think they are.

7596188
I doubt it. In reality, no generation of MLP was ever related to another sort of like later series of Power Rangers, Transformers, TMNT, GI Joe, and a couple of others I didn't mention. However, there are fanfics here that do make them related such as mine known as Destiny or Coincidence where the Mane 6 are actual descendants of the G1 ponies that are shown on the cover, but I just connected them with who Lauren Faust got the inspiration from. However, we may still see Sparkler, Posey, and Surprise since they were in the series, but most likely not Twilight (G1), Applejack (G!), and Firefly since they were from the original special and just limited to that. However, that may have to wait until part 4, though there are claims that Megan may be introduced in part 3, but that's only through inferences by bronies with the claim of the Rainbow Bridge being mentioned and that usually leads to her farm. Again, until we get there, we won't know what will really happen. Don't expect any G1 characters to appear in the part 2 either, though I wish that was the part the part they started to appear as it seems that the crossover is taking a backseat here.