The 23-year-olds will follow older brother Rob to the Premiership before returning to South Africa to play in Super Rugby for Natal Sharks in 2020.

Back row Jean-Luc made six appearances earlier this season for Sale during a previous loan spell until January.

Fellow back row Dan has played four times for his country, the last against England in Cape Town last June.

"Both lads are huge men with a commanding physical presence," said Sale director of rugby Steve Diamond.

Sale already have twins in their squad - 20-year-old flankers Tom and Ben Curry.

On Monday, South Africa prop Coenie Oosthuizen also agreed a move to Sale.