When I file for divorce, will I have to establish custody? If so, what are my rights and parameters as a father?

You can request custody as part of your divorce, but you don't have to wait until then.  You can file for custody at any time in the Juvenile & Domestic Relations District Court and the longer you wait, the more likely it is that your spouse will retain custody because there is a general preference for maintaining the status quo.  There is also a preference for children being with one of their natural parents as much as possible, so if you know you will be gone a lot and leaving the children with your mother, that means that your spouse will most likely get custody, if she is able to spend more time with the children.  However, if her living situation is really harmful to the children and you can show it would be in their best interest to live with you, then you could be granted custody.  But again, the longer you let them live in the current situation, the more it appears that you agree that it is okay for them.   This answer is given in accordance with the laws of Virginia and may not be applicable in any other state.  It should not be construed as legal advice, as that would require a more thorough analysis of all of the facts involved in a specific case.  If you need further information or assistance, please feel free to contact my office for a consultation. Case results depend upon a variety of factors unique to each case. Case results do not guarantee or predict a similar result in any future case.