Moses's wife and sons' and trips

Question

In Exodus 4:20 (NASB)

So Moses took his wife and his sons and mounted them on a donkey, and returned to the land of Egypt. Moses also took the staff of God in his hand.

and in Exodus 18:2-5 (NASB)

2 And Jethro, Moses’ father-in-law, took in Moses’ wife Zipporah, after he had sent her away, 3 and her two sons, one of whom was named Gershom, for Moses said, “I have been a stranger in a foreign land.” 4 And the other was named Eliezer, for he said, “The God of my father was my help, and saved me from the sword of Pharaoh.” 5 Then Jethro, Moses’ father-in-law, came with his sons and his wife to Moses in the wilderness where he was camped, at the mountain of God.

I presume Moses's wife and his sons never made it to Egypt or left at some point?

Answer 1

When Jethro, the priest of Midian, Moses' father in law, heard of all that God had done for Moses, and for Israel his people, and that the LORD had brought Israel out of Egypt;

Then Jethro, Moses' father in law, took Zipporah, Moses' wife, after he had sent her back,

... And Jethro, Moses' father in law, came with his sons and his wife unto Moses into the wilderness, where he encamped at the mount of God:

Exodus 18: 1,2,5 KJV]

Clearly, after the incident at the inn, regarding the issue of circumcision, and Zipporah's reaction to the necessity of circumcision, Moses had sent Zipporah back to her father.

Jethro then brings her back to Moses and brings also Moses' sons to him and gives Moses sound and sage advice regarding the government of the people in the wilderness.

Jethro then returns to Midian on his own, leaving Zipporah and the two boys with Moses in the wilderness :

And Moses let his father in law depart; and he went his way into his own land. [Exodus 18:27]

Answer 2

Exodus 18:2

After Moses had sent away his wife Zipporah, his father-in-law Jethro received her

When did Moses sent them back to his father-in-law?

I found the following answer from the Jewish Women's Archive:

In the midrashic amplification, Zipporah set out for Egypt with Moses, but never arrived there. Their parting took place on the way, following the encounter with Aaron. Moses and the latter met at the mountain of God when Moses was on his way to Egypt (Ex. 4:27–28). Aaron goes forth to greet his brother and hugs and kisses him. He asks him: “Moses, where were you all these years?” To which Moses answers: “In Midian.” Aaron further asks him: “Who are these children and women with you?” Moses replies: “My wife and my sons.” Aaron continued to question him: “And where are you taking them?” The answer: “To Egypt.” Aaron then tells him: “We are grieving for the first ones [the Israelites who are enslaved in Egypt], and now shall we grieve for these, as well?” Moses accordingly orders Zipporah: “Go to your father’s house.” Zipporah then departs for her father’s home, taking her two sons (Mehilta de-Rabbi Ishmael, Masekhta de-Amalek, Yitro 1).

Other rabbis concur that Aaron plays the key role in Moses changing his mind about bringing his wife and kids to Egypt:

Rabbi Judah Loew (known as the MaHaRaL) explains that it is logical to conclude that it was Aaron who convinced Moses to send his wife and children back. We can safely assume that Moses did not decide to send them back once he had arrived in Egypt, as that would have sent a very unreassuring signal to the suffering people: at the very same time that Moses promises salvation, he sends his own family to a safer place. It also could not be that Moses decided to send his family back on his own volition before his arrival in Egypt, as he himself had decided to bring them. The only option we are left with is that Aaron—who we know had gone to meet Moses in advance of his arrival—dissuaded him from bringing his family along.