This extension supports assigning and removing assgned related products,cross-sell product and up-sell products using the import/exports's dataflow wizard and it works in easy manner .
You just need to follow simple naming convention for your files while importing and these naming conventions are as below:-
1) For assigning related products your file name must have _rel like
2) For assigning up-sell products your file name must have _up like
3) For assigning cross-sell products your file name must have _cross like
After buying this extension you get the package file which you need to import from the magento connect.
All our csv files just keeps two columns first sku and second the skus of related,cross-sell or upsell products just separated by comma(,)