Seems to me you have a number of valid choices.

A. Treat the boy like shit and have your daughter grow exceedingly close with him.

B. Treat the boy like shit and have your daughter hate you.

C. Support your daughter, see the relationship fall apart eventually, and have a better relationship with your daughter in the end.
"I will slaughter them as a wolf among lambs!
The seas will run red with the blood of my enemies!"


-- Captain Hazel "Hank" Murphy, Sealab 2021