"He has played Zurich Premiership rugby and so comes to us with a great deal of experience particularly in defence. Simon is a strong player and will be a potent weapon for us in attack" added Bates.
Poised to make a return to action in European competition is centre Stephen Cranston, now almost fully recovered from the knee injury he sustained on Scotland's summer tour.
The Borders squad for the European Challenge Cup
Backs : Stuart Moffat, Gareth Morton, Nikki Walker, Simon Danielli, Jon Steel, Andy Turnbull, Stephen Cranston, Callum MacRae, Iain Berthinussen, Alistair Dickson, Joe Pattison, Charlie Hore, Alistair Warnock, Ciaran Beattie, Chris Cusiter, Johnny Weston
Forwards : Paul Thomson, Matt Parr, Bruce Douglas, Geoff Cross, Tom McGee, Steve Scott, Ross Ford, Will Kay, Colin Stewart, Scott MacLeod, Mark Blair, aKelly Brown, Andy Rennick, Scott Gray, Andy Miller, Wayne McEntee