Greetings and Peace be upon you.
Reincarnation is the re-birth of a being in a new body.
The concept of Reincarnation exists in Buddihsm and Hinduism.
In Abrahamic religion there is no concept of reincarnation (Islam, Christianity, Judaism).
The Idea of reincarnation exists in some Sects of Abrahamic Religions.

Source

Do you believe there is a reincarnation? Justify your belief.

I do not believe in reincarnation as it has no concept of existence in the light of Islamic teachings, this can be proved by 2 things;

• Concept of Hell and Heaven
• Prophet Muhammad ﷺ's Visit to the 7 skies (Heaven)

Concept of Hell and Heaven.

Muslims believe in the afterlife the believer and disbeliever has 2 destinations which they will be assigned according to their acts in this world. The person whose sins are heavy on his shoulder is destined to Haviya (HellFire) while the one whose good deeds are heavy will be able to enter Heaven.

Prophet Muhammad ﷺ's Visit to the 7 skies.

It is said the Prophet ﷺ Travelled through the 7 skies, a journey of millenniums which the Divine Prophet ﷺ completed in the blink of an eye and even lead prayer in Jerusalem for all the Prophets.

When he looked towards his right, he laughed and when he looked toward his left he wept. Then he said, 'Welcome! O pious Prophet and pious son.' I asked Gabriel, 'Who is he?' He replied, 'He is Adam and the people on his right and left are the souls of his offspring. Those on his right are the people of Paradise and those on his left are the people of Hell and when he looks towards his right he laughs and when he looks towards his left he weeps.'
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The encounter of the Holy Prophet ﷺ and our father Adam concludes that after death there is no second life but eternity in either Hell or Heaven.

Do you believe we get back our relationships through reincarnation? Describe.

Once again I do not believe in reincarnation, but it is said after death in Islam people can go back to their loved ones who they lost.

When I went over the second heaven, there I saw Yahya (i.e. John) and ‘Isa (i.e. Jesus) who were cousins of each other.
Source

Meaning both brothers united after reaching the afterlife, however, Jesus was still alive whilst John had passed away on Earth.

Do you like to be born just like what you are in this life;

Or would you wish to adopt any other person's life if there is a reincarnation? Explain the reasons behind your choice.

Humans are perfect beings as we are titled by Almighty Allah as "Ashraf-Ul-Makhluqat" meaning "the best of beings". So there is no reason why I would want to become another being if I had the chance to a second life.
This is elborated in many verses of the Quran, the most clear one is "Surah-Al-Teen"

Indeed we created man in perfect shape.
(95:4)
this is my entry in the "Do you believe in reincarnation" challenge from Islamic point of view. I hope you learned something new, God bless, take care.
I invite @roominaz @hamzayousafzai and @drhira