The new Welsh development regional sides will face the Irish provinces' A teams in a new tournament from 2018-19.
European Champions Cup winners Leinster announce the signing of Australian back Joe Tomane from Montpellier.
Ireland international fly-half Joey Carbery moves from Leinster to inter-provincial rivals Munster for the 2018-19 season.
Leinster celebrate the historic double after beating defending champions Scarlets in the Pro14 final.
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