Fly-half Brandon Thomson is to sign a two-year contract with Glasgow Warriors after his loan spell from Stormers.
Former Edinburgh head coach Alan Solomons warns South African teams joining the Pro12 would be at a "distinct disadvantage".
Scotland full-back Stuart Hogg is to see a specialist after picking up a facial injury on British and Irish Lions duty.
Glasgow Warriors are drawn against English champions Exeter Chiefs, Vern Cotter's Montpellier and Leinster in the European Champions Cup.
Audio & Video
Glasgow Warriors head coach Gregor Townsend looks back on some memorable moments as he prepares for his final match in charge.
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How to get into rugby union - into the thick of the 15-player game or try rugby sevens, which made its Olympic debut in 2016.
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What's on BBC Sport this week
This week's sport on the BBC includes The Open, the conclusion of the Women's Cricket World Cup and action from the World Para-athletics Championships in London