We have yet one more example of this. That is Hagar.
She was given to Abraham to wife. Who gave her to him? The one who had authority over her, Sarah. She remained Sarah's handmaid throughout this time though.
Gen_16:3 And Sarai Abram's wife took Hagar her maid the Egyptian, after Abram had dwelt ten years in the land of Canaan, and gave her to her husband Abram to be his wife.
After this, she began to despise her mistress, Sarah. Sarah was STILL her mistress.
Gen_16:4 And he went in unto Hagar, and she conceived: and when she saw that she had conceived, her mistress was despised in her eyes.
Then Sarah decided she wanted Abram to send Hagar away. Abram said to her, it is YOUR maid, you do what you will.
Gen 16:5 And Sarai said unto Abram, My wrong be upon thee: I have given my maid into thy bosom; and when she saw that she had conceived, I was despised in her eyes: the LORD judge between me and thee.
Gen 16:6 But Abram said unto Sarai, Behold, thy maid is in thy hand; do to her as it pleaseth thee. And when Sarai dealt hardly with her, she fled from her face.
Then Hagar was away from them and an angel came to her and told her to return and submit herself unto her mistress. She was still Sarah's slave.
Then at his death, the status of his wives becomes known for certain.
Gen 25:5 And Abraham gave all that he had unto Isaac.
Gen 25:6 But unto the sons of the concubines, which Abraham had, Abraham gave gifts, and sent them away from Isaac his son, while he yet lived, eastward, unto the east country.
Then to confirm that this is not thought in confusion, Paul affirms what I am presenting here also.
Gal 4:22 For it is written, that Abraham had two sons, the one by a bondmaid, the other by a freewoman.
Gal 4:23 But he who was of the bondwoman was born after the flesh; but he of the freewoman was by promise.
Gal 4:24 Which things are an allegory: for these are the two covenants; the one from the mount Sinai, which gendereth to bondage, which is Agar.
Gal 4:25 For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children.
Gal 4:26 But Jerusalem which is above is free, which is the mother of us all.
Gal 4:27 For it is written, Rejoice, thou barren that bearest not; break forth and cry, thou that travailest not: for the desolate hath many more children than she which hath an husband.
Gal 4:28 Now we, brethren, as Isaac was, are the children of promise.
Gal 4:29 But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now.
Gal 4:30 Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the freewoman.
Gal 4:31 So then, brethren, we are not children of the bondwoman, but of the free.
This should make it abundantly clear that Hagar was indeed a wife AND a concubine and a bondwoman/slave/not free.