Uncapped Wasps flanker Sam Jones has been included in the Barbarians squad for the games against England and the British and Irish Lions.
The Baa-Baas have confirmed 22 players who will form the core of their touring party, with former England U20 forward Jones joined in the squad by Wasps team-mate Marco Wentzel.
Other additions include Perpignan's James Hook and fellow Welshmen Dwayne Peel and Matthew Rees - all three who are former Lions representatives.
Players from 10 different countries are now represented, including Hong Kong Sevens skipper Rowan Varty, United States wing Takudzwa Ngwenya and Samoa scrum-half Kahn Fotuali'i.
"Our selection process has taken several months and is still not quite complete," Barbarians team manager Derek Quinnell said.
"Over the next week or so we will be monitoring the domestic play-off matches in Europe and the various national squads for the summer tours.
"Also, one or two players in the squad announced today may not be available for both of our matches, so we expect to add other significant names in the near future."
The Barbarians play England at Twickenham on May 26 before heading to Hong Kong six days later to face Warren Gatland's Lions.
Barbarians - Backs: J Payne (Ulster), R Varty (DeA Tigers and Hong Kong), T Ngwenya (Biarritz and USA), J Rokocoko (Bayonne and New Zealand), J Hook (Perpignan and Wales), N Evans (Harlequins and New Zealand), K Fotuali'I (Ospreys and Samoa), D Peel (Sale Sharks and Wales), D Yachvili (Biarritz and France).
Forwards: D Jones (Ospreys and Wales), B J Botha (Munster and South Africa), P James (Bath and Wales), M Castrogiovanni (Leicester and Italy), M Rees (Scarlets and Wales), L Ghiraldini (Treviso and Italy), M Wentzel (Wasps and South Africa), J Hamilton (Gloucester and Scotland), F Louw (Bath and South Africa), S Jones (Wasps), A Zanni (Treviso and Italy), S Parisse (Stade Francais and Italy), I Harinordoquy (Biarritz and France).