श्वशुरान्सुहृदश्चैव सेनयोरुभयोरपि। तान्समीक्ष्य स कौन्तेयः सर्वान्बन्धूनवस्थितान् ॥

tān samīkṣhya sa kaunteyaḥ sarvān bandhūn avasthitān kṛipayā parayāviṣhṭo viṣhīdann idam abravīt

Fathers-in-law and benefactors also in both armies; seeing all these kinsmen thus standing arrayed, Kaunteya,

In plain words: He also sees fathers-in-law and people who had been kind to him, in both armies. Arjuna sees that all of them are his relatives, lined up to fight.