It's too bad Luria isn't able to come to a compromise. I can understand where Alanna is coming from, but surely some Lurians are more pragmatic?
Saying you want Fissoa as a partner but denying it's cultural heritage won't yield much results. Hell, even Pianese or Askileon Empire would be more or less acceptable.
But perhaps we differ on the idea of empire itself. Skyn sees it more as a confederation, a structure above both Luria Nova and Fissoa. Perhaps you just see Fissoa as vassals.
Well, to address your second point first, the Empire is more or less the grouping together of realms with a hierarchy partially above the rulers of the realms, which can, to some extent, dictate their, and their realms', actions.
As for the other...I think you may have misunderstood the nature of the situation. This isn't Luria coming to Fissoa and saying, "Hey, why don't you and we get together and form an Empire, and call it the Lurian Empire?"
This is Luria Nova, sole current member of the Lurian Empire (which is, in fact, already making preliminary preparations to eventually split apart again, if all goes well, into multiple Lurian realms, united under the Imperial banner), asking Fissoa if it wants to join the Lurian Empire, which has existed, in one form or another, for some time now.
