When adding children, it is best to add the child first in FSFT and then add the parents to the child. Otherwise, you add the child to the father and then to the father and mother, leaving a duplicate connection between the father and child.
I’ve done it both ways. Can’t say one way is better than another. The important thing is to read how you are adding the person. If the father is already on FamilySearch, make sure to add the mother to him as a spouse, etc.