LOL.
I saw that on Feedbackgaming's video and nearly cried, then it happened again in my game (well, two of them now) and I almost suffered an aneurysm. :')
Never mind that the Byzantium tree grants cores to all the Turkish states EXCEPT Hatay lol...
The only way I worked around this was to rush Fascism via the Venizelos/EEE Byzantium tree, conquer Bulgaria before they joined the Axis/war broke out (since you can't justify as a democratic Greece). I then joined the axis and Germany STILL gave Bulgaria my cores (despite being my puppet), so I gave them tonnes of lend-lease until I could simply annex Bulgaria.
Hate to say it, but it's a heck of an oversight. This is also partially linked to another problem regarding Greek relations with Italy, who almost always attempt to justify on you no-matter the circumstances (this only cancels if Greek rush-join the Axis before an Italian DoW). Greece's "Rapprochement with Italy" focus should lead to Italy not justifying on Greece, but this would require Italy being able to access the "Befriend Greece" focus in it's tree. Given it is currently locked behind the "Italy First" path, this will almost never happen with an AI Italy (or even an axis player). I realise Italy will be reworked at some point in the near future (with Italy being alongside the Soviets as being MOST in need of new trees and general reworking), however they need some tweaks to make work done on BOTH DoD and subsequently with BftB fit properly into present game mechanics and focus trees.
On this note I do propose this slight modification to the tree, so Axis Italy CAN pursue friendship with Greece. To further compliment this, Greece ought to get a decision / event which could propose Italy to partition Albania, and one for an agreement over the Dodecanese. Whilst on the topic of focuses, I realise Greece ought to be in a pretty dire state and this is reflected in the diabolical national spirits Greece starts with, along with a pitiful number of factories. However consider allocating Greece 1 addition civ factory in one of the states suggested below (most likely Thessaly), and considering what few military factories exist in the focus tree, they all sit behind limited / mutually exclusive parts of the tree. Though they shouldn't start with more than 2 or 3 mil factories at game start, it would be nice if the "Hellenic armed forces" focus conferred even only a couple of factories.
Another point is that some further attention needs to be paid to the map and states in the game. I'm quite pleased they added Istanbul city, Amasya, Hatay and then Moesia to Turkey and Bulgaria respectively (Oh, and northern Epirus). However Plovdiv ought to be split north / south of the Marista river, with the northern state centered on Stara Zagora, and also incorporating Sliven and Yambol from the neighbouring state of Burgas. The state of Western Macedonia ought to be made from the western provinces of Central Macedonia and the north-eastern provinces that are erroneously part of Epirus. Likewise Thessaly/Thessalia as a new state centered around the city of Larissa, and ought to be made from the northern provinces erroneously part of of Attica and from the southern portions of Central Macedonia. Lastly since we have all the other Islands, make a new state of the Ionian Island from Corfu, Zakinthos and Cephalonia. Albania itself should be further split into a northern state called "Ghegheria" and the southern portion would remain "Albania" as is presently. As a final point, split the province of Alexandroupolis (the city along the Evros/Maritsa that is nestled between Bulgaria and Turkey) approximately into northern and southern provinces (this would help to reduce some of the gaminess of having Turkey throw it's army against one's bulk of the Greek army that can be focused into one single province).