Well, My only issue with this is that they HAVE to deal with a difficult resistant force. They can't jsut come into Hapan space, steamroll us, and say they have total control. It doens't work that way. If it didn't for Palpatine, then it can't for us.... and Palpatine lost, by the way. Hapes took what Star Destroyers they didn't destory. This is canon fact.
Anyway, I'm okay with it, if they play fair and acknowledge that they cannot get massive forces in to overwhelm us, because the Transitory Mists choke hypserspace near the hapes Custer. This forces invasive forces to Bottleneck, which means the Royal navy has the upper hand. They will have be extremely creative to seize our sovereignty.
I suggest working out a very long and drawn out campaign, full of skirmishes, poltical intrigue, and romance. The fringes of Hapan Space should become a heated battleground.... Seizure if hapes should not be quick and easy.
Addendum, considering the sheer size of the Consortium, total Sith control is impractical and probably not possible. We'de always have the capability of kicking them out, too... and that needs to be a condition of sith invasion should they win. Because frankly, I don't do storylines where the sith rule forever and no one has the ability to triumph over evil. So, yeah. We need to negotiate this out with those that want to make claim to Hapan Space. It has to be long, drawn out, and total defeat has to be possible for the Sith. Worst Case scenario, total control is not practical and not exactly possible, so they will frequently deal with insurrection and could either lose by attrition or seizure of military assets.... and any major atrocities, like orbital bombardment if they want to pull a space superiority means to control (as in no storm troopers and SS type folks on the ground, just big naval detachment to control space around our worlds, guns pointed at the ground... that kinda deal.. yeah, dealt with that kind of story before and I don't like it). Bascially, if they want us, they have to work pretty hard or it and even if they win, victory isn't total nor absolutely assured and should be able to change on a dime.
True, we're a minor faction, but that shouldn't mean we're pushovers.
Sooooo... help me come up with contingencies to make liberation sound and feasible should the worse case scenario happen?