Whose sisters were Zeruiah, and Abigail. And the sons of Zeruiah; Abishai, and Joab, and Asahel, three.

And their sisters were Sarvia, and Abigail. The sons of Sarvia: Abisai, Joab, and Asael, three.

and their sisters Zeruiah and Abigail. And sons of Zeruiah: Abishai, and Joab, and Asah-El, three.

And their sisters were Zeruiah and Abigail. And Zeruiah had three sons: Abishai and Joab and Asahel.

Sisters - i. e. half-sisters. Abigail and Zeruiah were daughters not of Jesse, but of a certain Nahash, whose widow Jesse took to wife 2-Samuel 17:25.
From the present passage, and from the fact that Abishai joined David as a comrade in arms before Joab 1-Samuel 26:6, it would seem that, although Joab was pre-eminent among the three 2-Samuel 2:13, 2-Samuel 2:16, Abishai was the eldest.

Whose sisters were Zeruiah and Abigail..... That is, sisters of David:
and the sons of Zeruiah; Abishai, and Joab, and Asahel, three; all valiant men and captains in David's army; their father's name is nowhere mentioned.