There was another question on the following topic. However, my question is different.
Rig Veda III.20.5
dadahikrāmaghnimuṣasaṃ ca devīṃ bṛhaspatiṃ savitāraṃ cadevam | aśvinā mitrāvaruṇā bhaghaṃ ca vasūn rudrānādityāniha huve ||
I call on Savitar the God, on Morning, Bṛhaspati, and Dadhikrās, and Agni, On Varuṇa and Mitra, on the Aśvins, Bhaga, the Vasus, Rudras and Ādityas.
The 33 Gods were mentioned here, as Vasus, Rudras and Ādityas and 2 Aswins.
In Rig Veda IV.1.2 Varuna was mentioned as the brother of AGNI and thus he was an Aditya.
As such, O Agni, bring with favour to the Gods thy Brother Varuṇa who loveth sacrifice, True to the Law, the Āditya who supporteth men, the King, supporter of mankind.
In the mantra Rig Veda III.20.5, apart from 33 Gods, Agni, Varuṇa and Mitra, who were already included in the list, were mentioned.