Balkan Slavic (Vranishte). Core cases mergers for nouns: Nominative and accusative are distinct, 1

брат, брата, брату; сестра, сестре, сестри/сестре; brat, brata, bratu; sestra, sestre, sestri/sestre
brat
brother(M).NOM.SG
brat-a
brother(M)-GEN/ACC.SG
brat-u
brother(M)-DAT/LOC.SG
sestr-a
sister(F)-NOM/ACC.SG
sestr-e
sister(F)-GEN/DAT.SG
sestr-i
sister(F)-DAT.SG
brother; sister
Type: Naturalistic spoken
Source: Mladenović 2001: 279-297