What does the Bible say about blended families? Are there examples that we can find in the Bible?
The Bible doesn’t really say much about mixed or blended families. Joseph was not really Jesus’ father but really his step-father, so to speak, so Jesus knew what it was like having to grow up with half-brothers and sisters, having at least four brothers that we know of, James, Joseph, Simon, and Judas (Matt 13:55) and also sisters, although since they are not named, we don’t know how many He had. The fact that He has “sisters” must mean that He had at least two of them (Matt 13:55). The fact is that blended families are not really mentioned much at all in the Bible besides the one that Jesus was raised in but Jesus was the only One Who had a different Father and that Father being God Himself. During Israel’s history, there were some blended families but this was due to the death of the men who were the primary supporters of the family and since the women sometimes had children to support, they usually remarried.
Boaz and Ruth
Although the marriage between Boaz and Ruth, both being in the line of Jesus Christ, was not exactly a mixed marriage, it was a marriage of mixed nationalities. What makes this remarkable is that God, under normal circumstances, forbids such marital arrangements. Ruth was a Moabite  widow and the daughter-in-law of Naomi, who was also widowed, and surprising, Ruth being a Moabite, she normally would have been considered a natural rival and enemy of Israel. They would later have a son named Obed who was the father of Jesse, who was the father of David, who is an ancestor of Jesus Christ (Matt 1). These types of marriages were the exception and not the rule but since there is no indication that God saw this as sin, this marriage was apparently allowed and for the purpose of sending a message to the later writer of the Gospel of Matthew. The fact that Jesus had Gentile blood mixed with in the blood of the Tribe of Judah, shows that Jesus’ death is applicable to all nations, tongues, and peoples groups of the world.
Is Polygamy a Blended Family?
In short, no, polygamous families are not blended families. According to the Bible, this is not what God thinks is best. In fact, God commanded the kings to not multiply wives (Duet 17:16-17) although they still did this as with the case with David , Solomon and most of the kings of Israel, each time it resulted in a dysfunctional family adding considerable heartache and family members betraying one another. If God told the kings to not multiply wives we can assume that He forbade this in the nation of Israel as well. The same goes with the Patriarchs. These families experienced a lot of conflicts due to jealously and rivalry of having more than one wife but sometimes, as with Abraham, it was the wife who suggested that her husband have another wife for the purpose of having sons so that the family lineage would survive.
The Blended Family of God
Acts 2: 5-12 “Now there were dwelling in Jerusalem Jews, devout men from every nation under heaven. And at this sound the multitude came together, and they were bewildered, because each one was hearing them speak in his own language. And they were amazed and astonished, saying, “Are not all these who are speaking Galileans? And how is it that we hear, each of us in his own native language? Parthians and Medes and Elamites and residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia, Phrygia and Pamphylia, Egypt and the parts of Libya belonging to Cyrene, and visitors from Rome, both Jews and proselytes, Cretans and Arabians—we hear them telling in our own tongues the mighty works of God.” And all were amazed and perplexed, saying to one another, “What does this mean?”
If you look at the Day of Pentecost, we get a hint that the gospel is going to be open to more than just the Jews, even though the church was dominated by them in the beginning. Acts 12:5 have the Parthians, Medes, Elamites residents of Mesopotamia, Judea, Cappadocia, Pontus and Asia, Phrygia, Pamphylia, Egypt, parts of Libya belonging to Cyrene, visitors from Rome, both Jews and proselytes, Cretans, and Arabians all asking “What does this mean?” Here is what I think it means. I believe that the family of God will include all nations from all parts of the world. Anywhere there is a person who repents and puts their trust in Christ they will become a member of God’s family, regardless of national origin. Paul, who became the Apostle for the Gentiles, wrote to the church in Galatia that “There is neither Jew nor Gentile, neither slave nor free, nor is there male and female, for you are all one in Christ Jesus” (Gal 3:28).
In John’s vision in the Book of Revelation, he saw “a great multitude that no one could number, from every nation, from all tribes and peoples and languages, standing before the throne and before the Lamb, clothed in white robes, with palm branches in their hands” (Rev 7:9). This gives every indication that God’s family is going to be a blended one and have every people group on the face of the earth represented in the coming kingdom of heaven. That is the way we should look at other brothers and sisters throughout the world…we are all one in Christ Jesus…all one family and all one, universal church. It is never about race but always about grace.
If you are not saved, meaning that you have never been born again (John 3:3), then you are not in the family of God and will be excluded from eternal, joyful fellowship with God and His children for all time. Your fate is so hard to describe that it cannot even be fully expressed by the Scriptures (Rev 20:11-15), therefore I beg you to consider repenting of your sins today, confessing them to God, and then putting your trust in Jesus Christ  to save you. If you do that, then you will forever be a member of the family of God and that family reunion will go on for time without end (Rev 21, 22).
Read more about family here: How Does God Define Family? 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), copyright © 2001 by Crossway, a publishing ministry of Good News Publishers. Used by permission. All rights reserved.