Little can be done proactively to stop a titled owner (or his or her agent or representative) from conveying property. A cease and desist letter from an attorney may cause the transferor to refrain from taking any improper action, but the letter itself would not have the effect of a court order, and the transferor could simply ignore it if he or she chose to do so. Another option might be to get an injunction prohibiting the transferor from conveying or otherwise encumbering the property, but injunctive relief is an extraordinary remedy, and would require the filing of a lawsuit in any event.
On the other hand, when a quiet title action is filed, a "lis pendens" is also recorded in the real property records of the clerk and recorder for the county in which the property is located. The lis pendens gives notice to the world that litigation is pending with respect to the subject property and that any potential purchaser, assignee or person encumbering the property will take it subject to the outcome of the litigation. This has the practical effect of scaring away potential purchasers who don't want to "buy" a lawsuit. Unfortunately, however, you can't can't record a lis pendens before the lawsuit is filed.
Finally, if a titled owner of property encumbers or conveys the property in an effort to defraud creditors, of for some other unlawful purpose, it may be possible to have the transfer set aside.
These are some of the issues you may wish to discuss in detail with a competent attorney.