Exodus 2:18 And when they came to Reuel their father, he said, How is it that ye are come so soon to day?
Exodus 3:1 Now Moses kept the flock of Jethro his father in law, the priest of Midian:
Judges 4:11 Now Heber the Kenite, which was of the children of Hobab the father in law of Moses, had severed himself from the Kenites, and pitched his tent unto the plain of Zaanaim, which is by Kedesh.
Reuel? Jethro? Hobab? Moses must have been asked that question a lot: "Who's your daddy?"
The most common answer: It's actually just the usual Ancient Near Eastern practice of multiple names for persons and cities according to context, just like Yahweh and Elohim. We agree, but add some more.
"Reuel" means "friend of God" and it is most likely an actual name, but the word used for "father" is 'ab and this also refers to the chief patriarch of a clan. Reuel, as the chief patriarch, was the one who arranged all the marriages for his female descendants. He was most likely a grandfather (or perhaps great-grandfather), which the word combination father/daughter allows.
"Jethro" actually means "his excellence" -- yes, in light of the Beverly Hillbillies, that seems strange, but it is a title, not a name as we have become accustomed to thinking.
That leaves "Hobab" in Judges. Who is that? That one is what we indeed would call, exclusively and legally, Moses' father-in-law.
Some Skeptics try to add Numbers 10:29 in the mix here, but make sure they quote it fully: "And Moses said unto Hobab, the son of Raguel the Midianite, Moses' father in law..." They leave out the part about Raguel, which is merely a linguistic variation of Reuel. But it actually serves to prove our point: Reuel was the lead patriarch; Hobab was his son and Moses' father-in-law as we define the term.