How to Keep Joint Custody While in Jail, Falsely Accused of a Sex Crime

My question involves a child custody case from the State of: AZ

The mother is behind a false accusation of child molestation while attempting to gain full custody of the children. She originally filed for sole custody of a 12 and 15 year old a few months ago after a dispute with the father; when the father contacted the courts about it, they basically said that since the children are older and there had been no issue brought up in the last 6 years since the divorce, that they needed to work it out themselves. Now the father is in jail awaiting trial and she served papers for an Appeal to Modify Existing Custody and Parenting Time and Child Support. He is feeling rather hopeless as to what he can do about it given the circumstances and we can't afford another lawyer. What steps can we take to make sure he still has joint custody once released?

There's no possible way to "make sure", even WITH an attorney. The step he CAN take is to respond to the modification request and make his case before the court. Given the nature of the criminal charge, realistically the best he's likely to get is some sort of supervised visitation pending the outcome of the criminal case (and of course if he stay in jail until his case, that's moot). Whether the court will give that request serious consideration is really going to depend on the specifics of the accusations, who made them, to whom, and other details. Once the criminal case is over, the court can re-assess in light of the outcome.