Imam Ali al-Rida

'Alī ibn Mūsā ar-Riḍā (Arabic: علي ابن موسى الرّضا‎), also called Abu al-Hasan, Ali al-Reza (c. 29 December 765 – 23 August 818) or in Iran (Persia) as Imam Reza (Persian: امام رضا‎), was a descendant of the Islamic prophet, Muhammad, and the eighth Shi'ite Imam, after his father Musa al-Kadhim, and before his son Muhammad al-Jawad.

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Sayyed Muhammad Husaini Ragheb, Sayyed Muhammad Husaini Ragheb has a BA in Law from Guilan University, Iran and has also undertaken Hawzah studies in Qom. He is a Cultural Affairs director of Ethics Group of Al-Mustafa Open... Answered 1 month ago

Sheikh Mufid (r.a) and Ibn Shahr Ashoub (r.a) have only recorded one son for Imam Reza(a.s) and he is Imam Muhammad al-Taqi al-Jawad (a.s) but some other historians have recorded five sons and a daughter for him.
As for Imam Jawad (a.s) the sons are Imam Ali al-Naqi al-Hadi(a.s) and Musa al-mubarqa' who is buried in Qom( Chehel Akhtaran) and he also had a daughter named Hakimah Khatoon who is buried in Samerra,Iraq.

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Sayyed Mohammad Al-Musawi, Sayyed Mohammad al-Musawi is originally from Iraq and heads up the World Ahlul Bayt Islamic League in London. Other than being involved in various humanitarian projects, he frequently responds to... Answered 7 months ago

There ae different opinions among the scholars in this matter.

Al Haafidh Abu Na'eem sated in Hilyat Al-Awliyaa that Ima Al-Ridha had six sons and Jafar is one of them.

Mohammad Ibn Talha al-Shafi'ee had the same opinion. 

Many of our scholars including Shaikh Al-Mufeed and Al-Erbily narrated from Imam Radha (AS) that he wl have only one son (Imam Al-Jawad) and Allah (SWT) will grant this one son lot of sons.

Wassalam