The best way to say that phrase and tell it to any Spanish native speaker from any country would be:
"Tienes/Tendrías que conocer a tu nieta, así ella le podría comenzar a tomar cariño a su abuelo"
And written in Argentinian Castilian (as you did it in your question) would be:
"Tenés/tendrías que conocer a tu nieta, así ella le podría comenzar a tomar cariño a su abuelo"
I hope it'd helped you!
Critian