Let's imagine those two women Anna and Julia who meet those two orphaned siblings Martin and Kasia. Martin and Kasia went to Anna and Julia to talk with them about their Mom.
Anna and Julia remember Martin's and Kasia's mother. These women remember their mother.
How else would you translate this sentence ?
In Polish if Anna and Julia remembered their own mother we would say "Te kobiety pamiętają swoją matkę"
no. In this sentence it is clear that it is plural
"te kobiety pamiętają"
te is (nominative = accusative plural form of "this", here in nominative, because it's the subject) ,
pamiętają is plural form of verb ( verb has to agree with a subject)
kobiety can be singular genitive or plural nominative or plural accusative. In this sentence it's the subject so it's plural nominative
You can see a chart here https://en.wiktionary.org/wiki/kobieta.
Polish nouns technically have 14 forms, but in reality some forms are the same for different cases.
It is often that feminine nouns have singular genitive=plural nominative.
Also all not masculine personal nouns have plural accusative=plural nominative=plural vocative)
You can tell form the form of adjectives and pronouns (plural te kobiety; singular genitive tej kobiety, and from function in the sentence, here it's subject it has to be nominative, if it's direct object you sometimes can tell knowing which case the verb requires.
There are some specific situations when it's ambiguous but it's rare. (and usually adding pronoun or adjective clarifies it)
Kind of. Polish third person possessive pronouns are derived from the genitive of subject pronouns. Since the genitive of both oni and one is ich, this pronoun can be used for both plural genders.
Some might disagree with my interpretation and say that ich should be regarded as a possessive pronoun which just happens to not inflect for gender and case.