You might want to show that elder the following from the Watchtower magazine October 15, 2006, pages 18-23)(HONORABLE WEDDINGS)
"14) In some lands where customary marriage is recognized as legal, there are also provisions for civil (or, statutory) marriage. A civil marriage is usually carried out before a government agent, and. it may include both taking marriage vows and signing a registrySome Christian couples prefer this civil marriage to a customary one. There is no legal need for both; each procedure is legally valid. What is said in paragraphs 9 and 10 about a wedding talk and vows applies here too. The main thing is that the couple are married in a way that is honorable before God and man. -Luke 20:25; 1 Peter 2:13, 14."
Taken from the following:
http://www.jehovahs-witness.com/10/124683/2205590/post.ashx#2205590
And I will give credit to Blondie here