When a marital relationship is good, spouses are appropriate guardians for each other. Marital relations can go bad, however, and in such cases spouses may cease to be appropriate guardians.
Michael and Felos convinced the Schindlers to agree that Michael was an appropriate guardian, by telling them that it would increase the malpractice award that could be won for Terri's care. The Schindlers didn't realize what Schiavo/Felos had in mind when they made that request.
Unfortunately, once guardianship is acceeded, it's very hard to challenge it. Had Felos not been allowed to fire Terri's guardian ad litem, that person could (and likely would) have filed for divorce. Unfortunately, since Judge Greer refused to appoint another guardian ad litem (required if there's any possible conflict of interest between spouse and ward) nobody could recognize Terri in court.
Thanks for clearing that up. It's my understanding that once someone is made guardian they pretty much can do whatever they want and the courts go along with it. So once Schiavo got himself appointed Terri's guardian the family had nothing to say. That's the principle of law the judge has been so determined to uphold, apparently. But in this case the conflict of interest seems so obvious that there should have been a permanent guardian ad litem. The judge ruled there was no conflict of interest, however, and no need for a continuing guardian ad litem and it's been a battle for the family ever since. The average person probably couldn't imagine that the law - and a judge - could stray so far from common sense yet it did and it does.