Davening next to one’s father [front, behind, or side]:
Some Poskim rule that it is forbidden for one to pray directly in front of or behind or to the side of his father within four cubits just as it is forbidden for one to pray behind his Rebbe. Other Poskim, however rule that it is permitted to do so, and that this prohibition only applies to ones Rebbe. Even according to the former opinion, a child may certainly sit next to his father for the sake of his education, and as requested by the father.
 See Pesakim Uteshuvos 240:6; 242:23; Encyclopedia Talmudit Erech Morah Av Vaeim Vol. 42 p. 583 footnotes 227-228
 Chayeh Adam 22:6; M”B 90:73; See Admur 90:23
 Binyan Olam Y.D. 47
 Ishei Yisrael 9 footnote 68