Property Acquired by a Parent Outside Marriage

My mom was awarded with a land in 1986 in Pembo, Makati. Unfortunately she had used my father's surname even if they are not yet married. And now that they are separated  for years and my dad had married another woman and he died last January, how would that affect the property acquired by my mother? Does the legitimate family has the right to take a share with it? Please help. Thanks.

when did they actually get married? if it was after 03 august 1988, then it became conjugal property and your father's heirs have a right his share int eh property.

They were just lived in partners. They separated without getting married last 1989. And my father married another woman legally that same year. Are my parents co owners of the property because my mom had used my father's surname even without marriage? And does my step mom has the legal rights to claim the said property in whole? how can it be conjugal when it was my mom who took the initiative to look for and paid some of the expenses for the said property?

And one more thing po, my family had been away in the said property for quite long. And when we returned and started living again to the said property, my Dad had built some additions to the old house (we are currently staying) and and had it rented with 3 different families before he died. Since my return I have talked to the tenants that they should give me their monthly rental fee instead of giving it to my step mom because in my opinion she does not have the right to do so? Am I right? Or should I just asked them to leave to avoid the conflicts because they do not want to give their monthly rent to me or to my mom.

they were never married so your father has no rights over the lot.