Explanation of the Ceremony of  'Datar'  
This is an excerpt from 'Hindu Customs and Beliefs'

Last Sunday I had an interesting visitor. She is getting married soon and hence wanted to know about the significance of Hindu Wedding  Rituals.  She and her fiancée would like to have a marriage ceremony with a difference. They feel that they would  both be contributing equally towards the working of their marriage. Therefore the to-be groom is inclined towards the desire to perform 'datar' with his in-laws, just like the to-be bride is required to enact with hers. 

Amongst the Sindhis during the ceremony of  'Datar', salt is exchanged from the bride's hands to the groom's hands three times. The bride also does the same with all the relatives from the in-law's side.  It is commonly believed that if you do the above there will be no arguments or fights between the bride and the in-laws. When salt mixes with food, it loses its identity, it mingles totally with the ingredients of the meal.  However the presence of the salt is felt because it gives the food taste.  By exchanging salt, the family subtly tells the bride that she is going to be part of the new family and she should mingle with them like salt does with food. 

Amongst the Hindus it is also believed that if you eat the salt of anybody's house, you ought always to be faithful to that family. Exchanging salt is also symbolic of the above. The bride-to-be would like her sister to participate in the marriage ceremony as much as her brother and uncles would be required to do. She asked me whether she was breaking any Religious rules thereby.  I assured her that the above ceremony was relevant to those times when it was only important that the bride adjust with her new family. I laud the bride and groom's spirit . I appreciate their desire to modify the Rituals and follow what their hearts proclaim is the truth of the day.