Is it true that Gosalyn may be related to Morgana?
Well, not based on anything that the series has ever actually indicated. The only places I’ve seen that theory put forth have been in fanfics. Not that there’s any direct evidence to contradict it – in fact, the show not only gives them a very slight resemblance in character design (green eyes, round faces – well, it’s SOMETHING), but Gos is very very interested in the “Monster” lifestyle and likes the idea of magic. Morgana’s father and other relatives find Gosalyn interesting, too – her spirit apparently is a lot like what Monsters would use to perform magic, things like that. But the series never actually suggested any relation between them.