Under what conditions would a conditional release be approved for an enlisted Marine trying to become an Officer in the Navy?

I left the USN and went US Army CWO in 1987. Check first to see if the DOD reg has changed BUT that DOD regulation stated any enlisted personnel that has been approved for a commission in any other branch of the service is to be release from their enlisted obligation for the purpose of attending their officer candidate school. As I said CHECK FiRST. The USN was NOT happy, gave me an honorable discharge ("At the convenience of the government") with an RE-3 re-enlistment code per regulation (RE-3=never to return) and I became an Army Warrant for the next 10 years. You also want to ensure your enlisted records and pay records are current and up to date. That can affect your officer's pay later on. For instance, my sea pay in the Navy counted towards my Army sea pay and I maxed that out as an officer since I had three years consecutive. (DOD reg for sea pay).

Can I ask why you want to commission into the Navy? You have already done Boot Camp, and having done both USMC boot camp and OCS I can tell you that if you have completed one, you can do the other. Unless you are pursuing a unique job in the Navy (i.e. medical services) IMHO it would be better for you to go into the Marine Corps as an officer. The Marine Corps has many programs that allow for direct commissioning, and as a Sergeant, you already have the troop leading characteristics that make a good officer great. The Marines will look to you as someone they can trust and respect - and it is your duty to MAINTAIN that! Additionally, as a Navy Officer you will always carry that USMC pride with you. This works as a double edged sword as we as a service are taught mission accomplishment and troop welfare go hand in hand whereas others are not. Having spent almost two years aboard ship and seeing this first hand it will often cause internal strife between what is right, what is expected and the limitations on what you can do.
I read that you have a wife and kids, so you also need to think about time away from family. Navy deploys for a long time and often. At least the Commandant has recognized this as a problem and is working hard to increase dwell time between deployments.
Regardless your reasons, I applaud you for having the discipline and determination to take time out of an already overwhelming work and family schedule to get your degree. Your dedication will carry you far in this world - God Bless and Semper Fi!

I am reading that your desired end result is to be released from your active duty US Marine Corps contract in order to attend US Navy OCS. If that is the case, if you do not try the answer is, unequivocally, NO. If you apply, the answer may be YES. Give them an opportunity to say yes and submit the request.