Courts do not like to meddle with changes to child custody agreements unless it has been determined to be absolutely necessary. This is because they only want what is best for the child, and usually some sense of continuity and routine is very good for a child -- it can be detrimental and confusing for a young person if his or her routine has been disturbed.
There may, however, be some more extreme circumstances where you as a parent and custodian deem it necessary for the child custody agreement to be changed. This may be because a significant detail in your or the other parent's life has changed, or because you have attained some new information that changes the current circumstances.
Reasons why child custody modification may be necessary
If you learn something new about the conditions that your child is living in while with the other custodian, you may feel urged to seek a custody modification immediately. This would be acceptable by the courts if there is an imminent danger to the child. Perhaps there have been occurrences of domestic violence in the home, other forms of abuse or a suspicion of drug use.
How the court deals with this
The courts will take into account the urgency of the matter and the potential for negative impact that the current situation might have on the child. If you believe that the current situation is negatively impacting the child in question, then it is a good idea to go about filing for a child custody modification. It is important to read up on the process before starting an application and the help of an attorney can be very beneficial.
Source: The spruce, "5 reasons child custody modification," accessed Oct. 18, 2017