The Exiles, who finished bottom of the Aviva Premiership this season, confirmed that Michael Hills is to join Doncaster, and Ed Williamson has agreed terms with Rotherham.
Doncaster-born Hills, who joined Welsh from Sale Sharks in 2009, made 91 appearances and is also an England Sevens international.
Williamson, meanwhile, will combine playing with coaching the Rotherham forwards when he moves to Yorkshire.
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