Regarding Gethsemene, I was there, and yes, we did attack it with hastur back then, also Keffa to get rid of Ashborn with the god that came before hastur, cant remember which. (But Shhhhh... you only heard it here) I have to admit, we only broke with the Netherworld because they wanted us to destroy Heen next, which was simply out of the question, lost a lot of nobles and land because of that. (that was the third invasion) Regarding the destruction of Ashborn and taking Geths we (or I) assure ourselves today that we had every right to do so as we hated Ashborn, and OG (much larger than it is even today) helped them the day we conquered Keffa without outside help, despite the fact we had a deal with King Lorgan, I think, that OG would never interfere in this 'civil war' before the invasion (Once upon a time Sint was an Ashborn colony) Also, the daimons were actually named after our gods, how cool is that!
But man, that's old history, then came the war between Old Grehk vs Neo Grehk, with us on the side of NG, then the reunification of the two and us helping the very reluctant OG, with key players from NG to help our cause, against Fronen that turned on OG the minute NG and OG reunited. I remember how brutal that 'civil war' became in the later stages, and how Purple Recluse (ruler of Melhed) helped broker a deal between me and Zog? when OG basically was just Ossmat and one or two regions. Then came Stephen (former ruler of NG), then Skye Uceek and I think two more, but cant remember. All of which Sint and Heen and much later Mesh were helped against the big powerhouse of Thalmarkin, Melhed, Avalon, Enweil and Fronen which more or less gave OG the choice between 'give up everything you lost already and help us against Sint or die' not the best of proposals, well in the end I can't complain because Sint gained an ally. By then, we had helped against Fronen in three very important battles, so favor was already more on our side. BTW I think I have at least three assurances of OG kings and queens that they will 'never' reclaim Gethsemene, but I guess that part of history never made it into the books.
In the fourth invasion we did only ally with the daimons because we knew it to be a matter of survival. I had constant reports from the north with up to three daimon leaders in a region with stacks of up to 30k each, and we knew we were only poking at the outer shells of that onion. I knew we had to bide our time or get eradicated, even tried brokering a deal to get Heen and Mesh out of the doghouse, but they just wouldn't listen. Well, so we waited, didn't lift a finger to help the daimons in any way and sided with the 'light' the minute they appeared on our borders. Oh man, Prudent was MAD. I think it even went so far that he was mad at me personally for betraying his trust...
Regarding the latest invasion, the blighting of Firbalt broke our backs, morale was so low, we couldn't gather our army anywhere, people just wouldn't log on regularly enough so that of the 20 nobles in our main army only 4 made it to the rally point in time. Not only that, but we simply did not have enough money to support a decent army. Keffa is actually rather poor and Gethsemene was sacked once or twice with only half its normal population. Don't forget Fianik was a portal and a quarter of Overlords troops came from there, committing genocide on their way south and east.
As for Gethsemene today, I think it would be very hard for OG to convince Sint to give it up. By now we regard it as a core region of our realm, and given how OG was able to expand before the invasion and reclaim nearly all its lost territory including four townsland regions, I think it's safe to say, OG will be stronger than Sint for quite some time (given that Fianik has less than a thousand pop at the moment). Once we reach parity I think negotiations are indeed much more in favor of OG but given how time and chaos will play a factor, who knows how the map looks by then.