adverb
alternately; in turn; one after another
Describes people doing something in rotation or taking turns. Often used when multiple people share a task or activity.
三人の子どもが代わり代わりにピアノを弾いた。
The three children took turns playing the piano.
会議では、参加者が代わり代わり意見を述べた。
At the meeting, the participants gave their opinions one after another.
交互に means 'alternately' in a strict back-and-forth manner, often between two parties. 代わり代わり can involve more than two and implies a looser rotation.
Reduplication of 代わり (かわり, 'substitute' or 'alternation'), with the second element voiced to がわり. The reduplication emphasizes the alternating or rotating nature of the action.