I would think that whoever the child lives with there would be a greater attachment. That's not to say the "parents" wouldn't be loved but it's the full time,day to day caregiver that the child will have a greater attachment to.
That's to say for an example if your child goes to day care or even school,that child doesn't become attached (love) the daycare provider or teacher more than the parent.
The influences you have with your child,the caring of,loving words,playtime,kissing boo-boos,and yes,even discipline,family times,all that is what molds and shapes our children.
I'm not sure what the exact situation is that you are facing but as a parent I can sympathize with that worry.
Obviously a lot depends on the home life and the precise situation so it's hard to really answer but I hope this helped a little.