While it is clear that Indiana does afford step parents some rights in certain circumstances that other states do not - such as for rights of visitation in the event of a divorce between the step parent and the natural parent - I would highly doubt that a step parent has any right over and above the right of the child's natural parent.  That would in fact go against the grain in every state.  It would be tantamount to a severance of parental rights with out the necessary step of a court hearing on the issue.  I do not think that you need to quote the law if you are the natural parent.  In fact, I would absolutely refuse to even give any credence or credit to this argument at all. Dismiss it as you would any other absurd assertion on your rights as a parent and let the step parent know that if he or she continues to interfere in your rights as a parent you will seek legal intervention (like filing harassment charges).  Good luck.