Al-Nakha'i (may Allah have mercy on him) said that Sayyiduna Ali and Sayyiduna Zayd (may Allah be pleased with them both) said, concerning a man who left a full brother and a paternal half-brother, that the wala' is assigned to the full brother. If the paternal half-brother dies, the wala' returns to the sons of the full brother.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الولاء / 21497