Thanks for the chance to help. I am an attorney with over 12 years military law
Since you and your spouse are both subject to the UCMJ, both of you could potentially be prosecuted.
That said, there is no obligation to "cooperate"
In fact, under Art 31, UCMJ, you both have the right to give no information at all.
Under the law, both federal and military, there is no crime against marriage
between an officer
and enlisted soldier
. But there is a clear rule, as stated in the Army Command Policy, against illegal fraternization
So her command can not prosecute the marriage...but they can investigate the relationship prior to the marriage. If there is evidence of an improper personal relationship that pre-dates the marriage, her command could prosecute her for that.
But, as you describe, if you did not have an inappropriate relationship prior to the marriage? Then neither of you should have any issues.
That said, I sure would not help in the investigation...no reason to do so. Unless they can find evidence of an inappropriate relationship, they have nothing to prosecute.