Answer:
Given the various states' adoptions of Article 9 of the UCC, you should check your question out with local legal counsel familiar with UCC Article 9 as adopted in your state or the state whose law will apply.
The most current version of Article 9, adopted in many states, includes section 9-330, which permits a person entitled to priority to subordinate the person's security interest to that of another person with a security interest in the same property. The mechanics of subordination are also matters best checked out with local counsel.