Sebastian Kehl says Shinji Kagawa would be welcomed back to Borussia Dortmund with open arms.
Douglas has described his arrival at Barcelona as the pinnacle of his career ahead of their visit to Villarreal on Sunday.
Hearts winger Andrew Driver believes the club will continue in some way, shape or form regardless of what happens over the coming days and weeks.
The Edinburgh outfit is battling for survival after being issued with a winding up order by Her Majesty's Revenue and Customs over a tax bill of almost £450,000.
Club bosses highlighted the severity of the situation when they admitted next week's game against St Mirren could be their last unless fans help the club come up with the cash.
However, Driver refused to consider the prospect of Scottish football without Hearts.
He said: "It's Heart of Midlothian - it's not going to go away.
"It's a nightmare of a situation the club is in and we've got to get out of this situation. It's a massive club, with masses of history.
"It's a shame it's in this situation and we've just got to get out of it."
Hearts are the latest club to find themselves in serious financial turmoil following the demise of Rangers.
HMRC action forced the Ibrox club to call in the administrators in February, before they were consigned to liquidation in the summer and re-launched as a newco in the Irn-Bru Third Division.
Driver added: "It's the way the world is going at the moment.
"There are a lot of businesses elsewhere going the same way so it's not as though football is on its own in this situation.
"It's always a worry and, for people who have a chance of losing their jobs, it's not ideal.
"We've all got to pull together and do what we can to stop the situation."
Hearts are attempting to negotiate a payment plan with HMRC over the matter and have asked fans to buy tickets for forthcoming home matches and invest in a recently-launched share issue.
Driver believes all the players can do right now is deliver the performances that will drive fans back to Tynecastle, pointing out that they have produced the goods in the face of adversity in the past.
He said: "We are professionals. We've got to go into our game [at Inverness] this weekend and do as well as we can, as we have done over the last two years when we haven't been paid on time.
"We've kind of rallied together and got some pretty commendable results in those situations.
"It's just business as usual for us and hopefully we can get the siege mentality from this and go into the game and get a result.
"The statement on the internet was enough to show that the club is in dire straits and we do need support.
"Hopefully the fans can turn out to the next few games and support us.
"As players, we've got to put on a performance for these guys to keep the fans coming back.
"We've got to look at the way we have performed in the last few weeks and hold ourselves slightly responsible for that.
"We've got to try to bring the fans back and that's all we can look for and aim to do."
Hearts are under a Scottish Premier League transfer embargo following consecutive late monthly payments to some players and coaches.
Boss John McGlynn has indicated he would be willing to accept a voluntary delay in his wages to help the club.
Asked if the players would do the same, Driver said: "I don't know if we would have any option anyway.
"If the time comes, we will sit down and talk about it. As a group of boys, we are willing to look at options.
"We know the club is the greater purpose at the moment so we would have to sit down if the situation arises.
"I can't speak for the rest of the guys because we haven't talked about it but, when the time comes, I'm sure we will sit down and discuss it."
The 24-year-old joined Hearts as a youth academy player and added: "It's very worrying.
"The biggest thing for us is that the club is being honest with us and open with us. Nothing is being hidden.
"We know the situation we are in, which is always better.
"It's not ideal but it's not only us as players, it's the whole club - we are all in it together."