New Charlton owner Roland Duchatelet says supporters must accept that their leading players could be sold to Standard Liege in the future.
Duchatelet also owns Belgian league leaders Standard, who are on course to qualify for the Champions League.
He told BBC Late Kick Off London and the South East: "This club [Charlton] also needs to make money.
"It's not to be excluded that some players will be sold to Standard Liege and play Champions League."
Duchatelet has amassed a personal fortune of around £615m from his electronics industry and other business interests.
The 67-year-old took over at Standard Liege three years ago and has now built up a network of six clubs at various levels throughout Europe.
The same year that he acquired Standard, his son Roderick bought Hungarian top-flight team Ujpest.
Then this winter, Duchatelet Sr bought German fourth tier outfit FC Carl Zeiss Jena, completed his takeover of Charlton and acquired Spanish second tier team AD Alcorcon in quick succession.
He also used to own St Truiden (STVV), who are now in the Belgian second division and still owns their stadium.
In the January transfer window. Charlton sold midfielder Dale Stephens and striker Yann Kermorgant to Championship rivals while five of their six new signings came from clubs in Duchatelet's network.
"We [Charlton] will be a very realistic club in terms of what we spend," said Duchatelet. "The aim is very quickly to break even, so the fans should expect us to sell players once in a while.
"We will not keep them forever because that's the priority of the way we can pay the bills at the end of the year."
Standard Liege's sports manager Jean-Francois de Sart oversees the club's Formation Centre - the name for their youth academy which has recently spawned talent, including Premier League trio and Belgium internationals Christian Benteke, Marouane Fellaini and Kevin Mirallas.
"The objective is to share the players. When a player not good enough for the first team needs some experience he can go to Charlton," de Sart said.
"When we have a big talent of Charlton he can come also to Standard Liege."
De Sart also revealed that representatives from Standard and Charlton, and those of the other clubs in Duchatelet's network, are due to meet this week to "organise how we will work in the future".
Charlton and Standard Liege are the two biggest clubs in Duchatelet's network but he insists he will treat them equally.
"If you have five children what is the priority between your children? They are all your priority," he said.
"I think that is the right attitude."
Belgium's play-off system means Standard Liege are not guaranteed a place in the Champions League, even if they hold on to top spot for the remainder of the regular season, which ends on 16 March.
However, they would take forward half their points into a mini-league between the top six teams, with the winner of that going straight into the Champions League group stage and the runners-up having to qualify.
A place in the group stage of next season's competition would be worth an estimated £8m to Standard Liege, but that would be dwarfed by the £120m Charlton would accrue should they manage to return to the Premier League in the future.
Their current position in the Championship relegation zone means that won't happen for at least another year.
While Standard would appear to offer Duchatelet his quickest route to riches, some believe his long-term interests lay outside Belgium.
"My personal opinion is that he is looking for the TV rights of the Premier League," said journalist Thierry Luthers of Belgian radio station RTBF.
"He wants to be in two big championships. He asked people close to him to find him a club near London and a club near Madrid [AD Alcorcon]. That is very important for his strategy."
Duchatelet's network of clubs breaks no Fifa or Uefa rules, but if two of his clubs were to qualify for European competition only one would be allowed to compete.
"I think the clubs can run independently," said Charlton's non-executive chairman Richard Murray.
"What this gives us is a European scouting network that we could never afford as a Championship club."