The Barbarians hope Wales' most-capped player Stephen Jones will make his debut for the invitational club against Australia at Twickenham on 26 November.
Scarlet Jones has been named in the Baa-Baas squad, suggesting the 104-times-capped player is not in Wales' plans for the clash with the Wallabies in Cardiff on 3 December.
Wales have first call on home-based players within 13 days of Test matches.
However, other Welsh players have been withdrawn from the Baa-Baas squad.
New Zealand's World Cup winners Sonny Bill Williams, Jerome Kaino and Keven Mealamu are included along with South African stars Victor Matfield and Bryan Habana, former Australia captain Stirling Mortlock and Italy's Mauro Bergamasco.
But Cardiff Blues' Jamies Roberts and Ospreys Adam Jones and Ryan Jones must concentrate on Wales' preparations to face Australia a week later.
Roberts' team-mate, Leigh Halfpenny, was also in line to face Robbie Deans' side at Twickenham.
But the back-three star's chances of doing so were already threatened by an ankle problem.
And having not played since returning from the World Cup, Halfpenny could be involved with Wales without any game time since they lost 21-18 to Australia in the bronze medal defeat in New Zealand.
The participation agreement between the Welsh regions and the WRU gives the national team first call on players in the build-up to Test matches.
Fly-half Stephen Jones could line up for the Baa-Baas if he is not needed by Wales, with the Scarlets probably prepared to release him from Pro12 League duties.
The Scarlets face Newport Gwent Dragons on the eve of the Barbarians' match in London.
But if Jones is released for the Barbarians, he could be up against one of the sport's most highly-rated young stars James O'Connor, who could switch from the three-quarter line to fly-half in injured Quade Cooper's absence.
Scarlets coach Nigel Davies has stated: "If we can release him we will, but there's no guarantee. It depends on our needs."
Jones' fellow Scarlet Rhys Priestland is likely to be with the Wales squad on the night of the Dragons encounter, leaving Dan Newton, Aled Thomas Rhys Jones and Owen Williams as fly-half contenders.
Barbarians' secretary Alan Evans said: "We have had very positive talks with the coaching staff at the Scarlets.
"They fully appreciate the honour it would be for Stephen to play for us at this stage of his distinguished career.
"At the same time we must respect their fixture commitments next week and will have a final decision in the next couple of days."
Evans admitted they are disappointed some of Jones' Wales colleagues will not be in action at Twickenham.
He added: "We also realise that the Welsh regions and the Welsh Rugby Union's hierarchy have been incredibly supportive of us for similar matches in recent years.
"We look forward to inviting these players, and others, again in the near future."
Barbarians squad: Bryan Habana (South Africa), Isaia Toeava (New Zealand), Robbie Fruean (Crusaders), Stirling Mortlock (Australia), Sonny Bill Williams (New Zealand), Stephen Jones (Wales), Danny Cipriani (England), Peter Stringer (Ireland), Nemia Kenatale (Fiji), Keven Mealamu (New Zealand), Adriaan Strauss (South Africa), Salvatore Perugini (Italy), Sylvain Marconnet (France), Eusebio Guinazu (Argentina), Victor Matfield (South Africa), Simon Shaw (England), Marco Bortolami (Italy), Jason White (Scotland), Jerome Kaino (New Zealand), Adam Thomson (New Zealand), Mauro Bergamasco (Italy).
Australia squad: Ben Alexander, Adam Ashley-Cooper, Berrick Barnes, Pekahou Cowan, Dave Dennis, Anthony Faingaa, Will Genia, Scott Higginbotham, Matt Hodgson, Rob Horne, James Horwill (capt), Digby Ioane, Ben Lucas, Salesi Ma'afu, Ben McCalman, Stephen Moore, James O'Connor, Nick Phipps, David Pocock, Tatafu Polota Nau, Radike Samo, Nathan Sharpe, Rob Simmons, James Slipper, Ben Tapuai, Lachie Turner.