Let's make it perfectly clear for China.
The United States of America, by right of conquest recognized in the 6th Treaty of Paris, 1898, took over sovereignty of the Philippines Archipelago including the Batanes Islands from the Spanish Empire. The map from that treaty is below. The Batanes islands were later clarified in the Treaty of Washington ratified in 1901 and included within the revised dotted line. Other small islands in the Celebes Sea were transferred by 1930 treaty from Great Britain.
In 1946, the United States transferred ownership of the Philippines archipelago, including the Batanes, to the new Republic of the Philippines.
If China is making a claim on the Batanes, they need to take it up with the United States of America first.