wife swap makers sue us  copycat  the british producers of us wife swap are taking legal action against a show they claim is  a blatant and wholescale copycat  of their programme.  rdf media  which makes the show for us network abc  has filed a damages claim for $18 million (£9.25 million) against fox s trading spouses. abc bought the rights to the british show  which was first aired in 2003 and became a hit on channel 4. the us network is not part of the claim  but has supported rdf s action.  we respect our producing partners  right to protect their intellectual property in whatever manner they deem most appropriate   said abc in a statement. a spokesman for fox said it had not seen the details of the legal action and could not comment.  their show was first screened in june  and was criticised in the press for its similarities to wife swap. abc originally planned to call their programme trading moms  but changed it to avoid confusion with the fox version. earlier this year  the nbc network claimed that fox s boxing show the next great champ had been hurriedly produced to ensure its programme was the first to be screened. nbc alleged that boxing regulations had been violated  but failed in their attempt to have the show pulled. the fox show proved a ratings flop  while nbc s the contender is due to begin in february.