In Chinese culture, people believe that the proper sequence for marriage among siblings should be the elder before the younger. If a younger bride or groom gets married before an unmarried elder brother or sister, it is considered disrespecting the elder. Obviously, in modern times, younger siblings getting married earlier now happens all the time with less couples and families caring about this old tradition. But if you or your family is concerned about this traditional wedding rule and want to do something about it, here's what you can do:
What to do if you're getting married before your older brother
If you get married before your elder brother, you should buy him a new pair of pants as the Chinese word of pants ("褲" or "ku") sounds the same as wealth ("富" or "fu"). To show respect, the bride and groom will enter the bride and groom's new home under the elder brother's pants, which should be hung across the main door of the home. You'll need to make sure that the older brother is not at home when you enter the house for the first time. This act is to show respect to the elder brother and symbolize the couple being on equal terms with the elder brother despite his unmarried status.
What to do if you're getting married before your older sister
If you get married before your elder sister, you can do the same thing above but use a skirt instead of pants. However, some people may think it is not lucky to walk under a skirt so couples can solely just gift the elder sister a new skirt instead.
Couples should talk to their family beforehand to decide whether they should perform this ritual during the wedding day. Some might feel humiliated when their older family insists on this wedding custom but some might deem it necessary to show respect. In more modern times, the pants can also be substituted with a red string. This is a more elegant way to conduct this tradition and the couple may feel more comfortable with a smaller object.