As noted in another post on relocation, in order to relocate in violation of an existing custody agreement, you would need to show the relocation is in the best interests of the child. In other words, the move would offer financial stability, there would be sufficient social support, perhaps better schooling, or other factors that relate to being in the child’s best interest. In this case, the fact that the Dad is very involved in the child’s life makes the case for relocation more difficult. Dad, for example, could say that the move would lead to a diminished relationship which is not in the child’s best interest. He could also argue the move to a far away state harms the relationship and thereby may deprive the child of an important parental figure. In response, you could also point out that through advancements in technology, the father could still carry on a meaningful relationship through Skype or other online tools.
At the end of the day, however, you may want to consider whether or not you believe the move is in the child’s best interest. It would be wise to consider the impact on the child and whether the benefits of moving will outweigh the negative consequences of moving.
As always, I would need more facts to provide legal advice and I encourage you to seek out the advice of an attorney because this is by no means legal advice. Just to emphasize the point, in this blog post involving relocation, slightly different facts most likely lead to a totally different result. For more on relocation cases, check out this blog post and this other post on the subject.