The composition of the Roman family (familia) was not static but changed over time. The following general comments will provide the background for understadning the relationships in this play.
The head of the Roman family was the paterfamilias, the eldest living male of the family. This might be your biological father, but it might also be your grandfather, or an elder uncle. The paterfamilias is the only legal persona recognized by the civil law.
The "family" whether or not it is actually living under one roof could include the paterfamilias and all those who live under his power (patriapotestas.) This would include his spouse, all unmarried daughters, unmarried sons, married sons, their spouses and their children. It could also include other relations, freedmen, and slaves.
The make up of your family might also depend to some extent on the kind of marriage which the women in your family have (cum manu or sine manu); more about this later.
In the Aulularia you meet two families:
1. Euclio and his daughter Phaedria (we do not see her mother)
2. Eunomia and her son Lyconides (whose father is Antimachus) and Eunomia's brother and Lyconides' uncle, Megadorus.
Here are the Latin names of some of the main components of a family.
K. R. Bradley. 1991. Discovering the Roman Family: Studies in Roman Social History. Oxford University Press.
S. Dixon. 1994. "Re-writing the Family. A Review Essay," Classical Journal 89, 395-407.
------------1992. The Roman Family. Johns Hopkins University Press.
------------- 1990. The Roman Mother. Routledge.
J. Gardner and T. Wiedemann. 1991. The Roman Household: A Sourcebook. Routledge.
B. Rawson, ed. 1991. Marriage, Divorce, and Children in Ancient Rome. Oxford University Press.
-------------1992 . The Family in Ancient Rome: New Perspectives. Routledge.
P. A. Rosenmeyer. 1995. "Enacting the Law: Plautus' Use of the Divorce Formula on Stage." Phoenix 49, 201- 217
R. P. Saller. 1987. "Men's Age at Marriage and its Consequences in the
Roman Family," Classical Philology 82, 21-34
--------------1994. Patriarchy, Property and Death in the Roman Family. Cambridge University Press.
------------1984. "Familia, Domus, and the Roman Conception of the Family." Phoenix, 336-355
-------------1984. "Patria Potestas and the Stereotype of the Roman Family," Continuity and Change 1, 7-22.
B. Shaw. 1987. "The Age of Roman Girls at Marriage: Some Reconsiderations," Journal of Roman Studies 77, 30-46
Susan Treggiari. 1982. "Consent to Roman Marriage: Some Aspects of Law and Reality," Echos du Monde Classique/Classical Views 26, 34-44
------------------1991. Roman Marriage. Iusti Coniuges from the Time
of Cicero to the Time of Ulpian. Oxford University Press.