I am sure, you being a brother taking responsibility in your assembly, know the answer to the question posed. But let me reassure you that these are burdens we innocent believers are dragged into by some "well-calculated and scheming" people.
My comments are:
1. Once married silently and secretly to get police protection, by registration, trying to "brethrenize" the marriage in an innocent way is outright cheating of the assembly and the brethren.
2. If an elder had played along with it, it is a crime committed to the assembly and such an elder ought to be relieved of the ministry and responsibility in the assembly.
3. If any other persons, like local "agents" had played this game behind the back of your assembly, scripturally we can say that such "evil minded" brethren ought to be put outside fellowship until they repent of their sin against the assembly and prove their repentence by sitting in the back for some time.
4. If the couple had already married by registration, it must be checked whether they had already consumated the marriage. If so, then they are doubly cheating the assembly by trying to come and stand in front of the assembly to get married.(This cannot be proved even by medical examination, as we do not know for how long they were in "love" and lived together before they got married by registration).
5. I would also like to say that if these are all done without the knowledge of the family of girl or the boy or both, it is cheating of the third degree. At least the "so called believer" party ought to have informed his parents so as to evade the degree of heart ache they would go through.
6. These crimes are all matters outside the discipline of the assembly and done knowingly and willfully. Such people need to be disciplined and kept out of fellowship and announced publicly in the assembly so as to make it a serious warning to others, lest someone will be tempted to repeat these "games" to spiritualize their actions of trying to "save" such souls.