The story of Abhimanyu marrying Balarama's daughter, let alone Ghatotkacha helping with that, has absolutely no basis in Hindu scripture, as this article says:
Abhimanyu’s marriage with Balarama’s daughter Sashirekha or Vatsala is a unique story. This story is not to be found in the main Mahabharata narrative or in any Sanskrit literature or scriptures. It is a folk-myth developed by oral tradition.
The only wife of Abhimanyu mentioned in Hindu scripture is Virata's daughter Uttara, whom he marries in this chapter of the Virata Parva of the Mahabharata:
And then the nuptial festival set in between the families of the Matsya king and the Pandavas. And then conchs and cymbals and horns and drums and other musical instruments appointed by the Pandavas, began to play in the palace of Virata. And deer of various kinds and clean animals by hundreds were slain. And wines of various kinds and intoxicating juices of trees were profusely collected. And mimes and bards and encomiasts, versed in singing and legendary lore, waited upon the kings, and chanted their praises and genealogies. And the matrons of the Matsyas of symmetrical bodies and limbs, and wearing ear-rings of pearls and gems, headed by Sudeshna, came to the place where the marriage knot was to be tied. And amongst those beautiful females of fair complexion and excellent ornaments, Krishna was the foremost in beauty and fame and splendour. And they all came there, leading forth the princess Uttara decked in every ornament and resembling the daughter of the great Indra himself. And then Dhananjaya, the son of Kunti, accepted Virata's daughter of faultless limbs on behalf of his son by Subhadra. And that great king, Yudhishthira, the son of Kunti, who stood there like Indra, also accepted her as his daughter-in-law. And having accepted her, the son of Pritha, with Janardana before him, caused the nuptial ceremonies to be performed of the illustrious son of Subhadra. And Virata then gave him (as dowry) seven thousand steeds endued with the speed of the wind and two hundred elephants of the best kind and much wealth also. And having duly poured libations of clarified butter on the blazing fire, and paid homage unto the twice-born ones, Virata offered to the Pandavas his kingdom, army, treasury, and his own self. And after the marriage had taken place, Yudhishthira, the son of Dharma, gave away unto the Brahmanas all the wealth that had been brought by Krishna of unfading glory. And he also gave away thousands of kine, and diverse kinds of robes, and various excellent ornaments, and vehicles, and beds, delicious viands of various kinds, and cardinal drinks of diverse species. And the king also made gifts of land unto the Brahmanas with due rites, and also cattle by thousands. And he also gave away thousands of steeds and much gold and much wealth of other kinds, unto persons of all ages. And, O bull of the Bharata race, the city of the Matsya king, thronged with men cheerful and well-fed, shone brightly like a great festival.
And the only children of Balarama mentioned in Hindu scripture are his sons Nisatha and Ulmuka, described in this chapter of the Vishnu Purana:
Balabhadra espoused Revatí, and had by her Nisat́ha and Ulmuka.