"Les prenoms toniques" must be coordinated with the "prenoms personels"(person). "Lui" (him) coordinates with "il" (he). "Ils" (they) coordinates with "eux" (them). Ma mere/ma soeur = elle (her), the "prenom tonique" is elle but in this situation it means "she".
The verb avoir in french means “to have” and etre means “to be” they are both conjugated differently when used in different tenses but they are both still the most commonly used french verbs.