First of all, there are no rules. This is only a courtesy, but it depends on personal economic situation, but marriage is generally more festive. If you want to take 6 and 8 as flower girl, that is, 68 88 168, the wedding is usually led by some leaders or something. This may require more drivers, depending on what kind of car he gives you, and friends who are very close, that is, 88 or 168. Their best man has more red envelopes than flower girl. I'm from Chongqing wedding, hehe.