Its not like Materia grants you summons in BG&E, and alien infection and sorceress posession aren't all that similar to me. If Jade is married to some old guy named Cid in BG&E2 I'll give you that one. As for the antenna on a mountain, I don't really remember that in BG&E but really, where would be the best place to transmit? Highest places you can find I would think, perhaps a mountain top? Doesn't surprise me that they'd both come to that conclusion. As for lighthouse orphanages, I thinkg BG&E has a pretty good reason for it. Since they're on an island. A really rocky island. There's gotta be a lighthouse there. And if they're the only ones living on the island. Why not live in the lighthouse? I won't say it's coincidense, or inspiration, though it may be a combination of both, but really, I think they just came to a lot of the same conclusions independantly.