Family Traditions.....

I came from a family lineage with an age-long ancestral tradition. No male must marry any woman without her 1st getting pregnant 2prove her child bearing capability. My dad disobeyed during his own time & his 1st wife of 25yrs died without a single issue. Am the 2nd & only living son of my dad from his 2nd wife. My late elder brother was married for 5yrs with no issue.

My dad is old now & he insisted that  I must follow the family tradition & not make the same mistake he 1st made & that of my elder brother.
My girlfriend refused she wont take in b4 marriage so I tried my luck else where. Now 3 girls have come out to say they are pregnant for me....

Am confused, have  done DNA test for 2 & they are positive. Now my dad insisted I must marry d 2 of them, He wants to see  his grandchildren before  he dies

What should I do?