Find my grandmothers real father

Hello!
I don´t know how this really works, but if i am able to find my grandmother Elvys real father i would be very happy. I have been told that my great grandmother worked in the home of the Röhls. She got pregnant with the son in the house (Joseph i think) and my grandmother was born 03-23-1922. I was also told that my grandmother (Miranda) left her employment and that the Röhl family tried to find her. We live in Sweden but i am not sure where in Sweden my grandmother were when she worked in the Röhl family.

I know now a bit of my family on my fathers side and i would like to know more about my family on my mothers side. If anyone could help me i would be very greatful-

Rosemarie Hildenborg-Rosenheilm