Where will my borders be?

Any way to tell where the cultural border of a city will be, when it overlaps another city that is going to flip to another player?

I have just conquered Carthage and Utique from Dido. I am planning to keep Carthage and eventually annex it, it'll make a nice sea port for churning out a navy. Utique, though, I have no use for. However, Utique and Carthage overlap, and I would like to make sure that some of the strategic resources and lux's there wind up being mine.

I have two ways to dispose of Utique. The most natural thing would be to raze it, but I have also just brought Maria back to life as Dido had knocked her out. I could alternately gift Utique to Maria so that she will love me forever. She's going to be voting for me eventually in the World Congress so it doesn't hurt to buff her up a bit with an extra city.

Was thinking of razing the city a few turns, selling off anything too good for cash, then giving it to Maria.

BUT...

I don't know where those luxuries are going to be. If I use a GG to try and claim it after I gift it, that will make Maria hate me and undo the benefit of gifting her the city. If I don't do that, there's a real chance some of those luxuries will wind up being hers, whereas... I WANT THEM.

So is there any way to tell where the border between the two cities is going to be, after I gift Utique away?

The only safe way to dispose of the other city if you want the one you are keeping to hang onto all shared hexes within workable radius is to raze the other one to the ground and not sell it.

But in general, hexes will go to the closer city. This will still leave a bunch of hexes equal distance. The best guide is to remember what the boundary was between the time you captured the first city and before you captured the second.

You could claim the area you want with a Great General before gifting the city to her. The land it claims won't go to her I think.

Enhanced User Interface could be helping here. Hovering over a city shows the hexes it claims.

after you raze the city you could purchase the tiles that were not picked up or let them become part of your land by culture.