Would Bulgaria still have joined the Central Powers if it had gained more from the First Balkan War?
Short answerIts choice could have changed. Territorial gains enabled by British and French help would have given Bulgaria reasons to remain neutral or reconsider its alliances.
NotesA Bulgaria that reached Constantinople with British and French help would have had a strong reason to reconsider its later alliances. Its historical alignment with the Central Powers does not make the same choice inevitable in this counterfactual. An alliance would need to offer Bulgaria a realistic advantage. Bulgaria might have remained neutral or changed its alignment, with Italy providing the comparison.