Q: Could Earth (Urantia) be visted by another Paradise Son who would be born of woman and grow up as Jesus once did?
A: The answer is presented clearly in the following paragraph:
3. Bestowal Missions. The Avonal Sons do all, at least once, bestow themselves upon some mortal race on some evolutionary world. Judicial visits are numerous, magisterial missions may be plural, but on each planet there appears but one bestowal Son. Bestowal Avonals are born of woman as Michael of Nebadon was incarnated on Urantia. (20:2.7)
So no, that is not a possibility here. But, a Magesterial mission is definitely a possibility; following is a link to a very good study on future Magesterial Missions to our world. Magisterial Missions — Behzad Sarmast, UrantiaBook.org
Thanks so much for your question!