I don't think that Andre strategized to get Celestial to fall in love with Him. I think Andre was always close to Celestial. He was always there for her, in good times and in bad. I recall that at the beginning when Celestial had that argument with Roy, that he left the room, Roy knew that Celestial was going to call Andre. So apparently Andre was her refuge ever since they grew up together. It was expected that when Roy was in prison, she ran to Andre for comfort and consolation. So she must have fallen in love with him during that process. Andre was always in love with her, it was a natural feeling. So after all these years, I don't think this took them as a surprise.
Once Andre and Celestial’s daughter arrives, I think Celestial’s parents will come to accept Andre in their lives.