"As the sun appears in the morning and gradually rises to the meridian and then again sets in one hemisphere while simultaneously rising in the other, so Lord Krsna's disappearance in one universe and the beginning of His different pastimes in another take place simultaneously. As soon as one pastime is finished here, it is manifested in another universe. And thus His nitya-lila, or eternal pastimes, are going on without ending."
Srimad-Bhagavatam 3.2.7 Purport
"Srila Bhaktisiddhanta Sarasvati Thakura says that advanced devotees help the Supreme Personality of Godhead in His mission and that such devotees or personal associates incarnate by the will of the Supreme Lord. The Supreme Lord incarnates by His own will, and, by His will, competent devotees also incarnate to help Him in His mission."
Caitanya-caritamrta, Antya-lila 11.25
"The demigods are also associates of the Lord without personal touch, whereas the direct associates of the Lord are in constant personal touch with Him. The Lord and His personal associates incarnate in many universes without cessation. The Lord remembers them all, whereas the associates forget due to their being very minute parts and parcels of the Lord; they are apt to forget such incidents due to being infinitesimal. This is corroborated in the Bhagavad-gita (4.5)."
Srimad-Bhagavatam 1.15.49 Purport
"Krsna had 16,108 wives, and each wife had ten sons, and each son had another ten sons. In this way the whole family was composed of hundreds and thousands of men, Yadu dynasty. And when Krsna came, so to assist Him, all these demigods, they came to help Him, lila. Just like if you play something dramatic, you require so many assistants, so when Krsna comes, those who are devotees of Krsna, they also come to assist Him. Somebody becomes His father, somebody His mother, somebody His friend, somebody His wife, somebody His son, some grandson, like that."
Lecture on Srimad-Bhagavatam 1:15:22-23, Los Angeles, 12-2-73
Bhaktivedanta Book Trust. HDG A.C. Bhaktivedanta Swami Srila Prabhupada.