Amazing...a friend of ours was in court this week for child support and visitation. First time (baby 5 mos, CP/mother), she offered the NCP/father a very good visitation scheduled (judge was even impressed). Then as things were wrapping up, NCP/father asked if they could change the Wed overnight to Thurs. b/c step-mom works Wed. nights and wanted to spend time with the child too. Judge granted it and said it was in the best interest of the child to have quality time with his stepmother as well. CP/Mom even protested saying she worked Weds. and if they changed to Thurs. it would take time from her and the child. So, it looks as if some judges support step-parent relationships...
I see how some parents can use this method to try and alienate another parent, but not all people are this way. I'm simply saying...if mom/dad, step-parent, and child are comfortable with it ... it is not wrong. But, it is wrong if handled inappropriately...better?
But in the end...not against the law.