Fang Jintang and Qu Qianhe had complicated feelings toward Bai Ye because Bai Qianqian appeared so unexpectedly and her background was so bizarre that they initially were very guarded against her father. Later, as their feelings toward Bai Qianqian changed, their feelings toward her father gradually changed too, not to the extent of treating him as a son-in-law, but they did begin to appreciate him more.
Because Bai Qianqian was really sensible and clever, they felt that the person who raised her must be a good person.
Then later, when Fang Yuxin proposed to end her engagement with Qiu Yiming and Bai Ye appeared, they began to see Bai Ye as a potential son-in-law.
This is not to say that they immediately treated Bai Ye as a future son-in-law, but they began to evaluate him with the criteria they would use for a future son-in-law.
