שלום וברכה!
[אלול תשכ"ז]
כיון שיש בהנ"ל - צירוף ענינים:
שם הסבתא, האם, המדוברת תי', אח מבוגר וכו',
יושיבו ג' רבנים, שבודאי שקו"ט עפ"י שו"ת הצ"צ חאה"ע סקמ"ג דבר המשנה שבן ח"י לחופה כו', פי' חז"ל במ"ע דלדבקה כו', לישא בת ת"ח ולהשיא בתו לת"ח (הלכות דעות ו' ב) ועשית ע"פ אשר יורוך - בשעטומ"צ.
נדפסה בלקו"ש חכ"ד ע' 461.
דבר המשנה: אבות ספ"ה.
ועשית ע"פ אשר יורוך: פ' שופטים יז, יו"ד-יא.
Shalom u'Vrachah!
Since the above involves a combination of factors: the grandmother's name, the mother, the woman in question may she live, an older brother, etc., three rabbis should be convened. They will certainly deliberate and decide according to responsa of the tzt"z, Even HaEzer section 143, regarding the Mishnah's statement that a son at age eighteen is ready for marriage, etc.; as explained by our Sages regarding the positive commandment "to cleave," etc.; to marry a daughter of a Torah scholar and to marry off one's daughter to a Torah scholar (Hilchos Deos 6:2), and "you shall act according to what they instruct you"—with blessings for success. Printed in Likkutei Sichos vol. 24 p. 461. Mishnah reference: Avos chapter 5. "You shall act according to what they instruct you": Parshas Shoftim 17:10-11.
Summary
When faced with complex family situations involving multiple considerations, one should seek guidance from qualified rabbinic authorities and follow their halachic decisions as instructed by Torah.