Ibn Jurayj (may Allah have mercy on him) narrates from Ata (may Allah have mercy on him), concerning a man who died leaving a brother and a grandfather, that the wala' is shared between the grandfather and the brother.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الولاء / 21508
Sayyiduna Zayd bin Thabit (may Allah be pleased with him) said: The grandfather is more entitled than the nephew and the paternal uncle, and this is what people practise.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الولاء / 21509