Let's assume that the divorce will be a civil one and that the parties want to seek an equitable division of the marital assets.

The easiest way to handle it would be for the one with the miles to sign an agreement that tickets will be issued at the request of the one without miles up to the 50% of the total miles available at the time of divorce (or at a suitable point in time).

This makes it better for both parties, so that the one with status can have the tix or certificates issued with the greater leverage. Being EXP with a boyfriend who is GLD, I am the one buying a tickets for his family all the time--from my account it is a breeze.

The "Unexpected Legacy of Divorce" by Wallerstein is a good read on the consequences of divorce. I'd recommend it to all parties in the situation.