Duryodhana was the father of Lord Krishna’s son, Samba’wife Lakshmana.
Hence Duryodhana was the Sambhandhi or Beegaru of Lord Krishna.
There is no equivalent word in English to describe this relationship between Krishna and Duryodhana based on this relationship.
(Anglophiles may note that English language does not have words for many relationships as well whereas one can find suitable terms in Indian languages and dialects even for relationships that are far removed)
Samba, a son Lord Krishna through Jambavathi kidnapped Lakshmana, daughter of Duryodhana and in the ensuing battle was captured and imprisoned by the Kauravas..
Balarama, elder brother of Krishna and Guru of Duryodhana for wrestling, inteceded , had Samba released and had him married to Lakshmana, Duryodhana’s daughter.
This is narrated in The Sambapurana, an Upa Purana.
Shall write information on lesser known events from Puranas and Ithihasas.
Reference and Citation.