On top of domestic competitions, it remains to be seen what will happen with the Champions League and the Europa League, with both competitions requiring teams to travel between countries, something which is particularly hard at this time.
"As responsible leaders, this is what we have to ensure, as long as there is a last chance and as long as there are solutions available", the respective Presidents said in the letter.
In Belgium, the decision was made on Thursday to abandon the season after 29 of the 30 main round match days and forego the play-offs.
The Federations are encouraged to avoid rash decisions in a letter from UEFA, the European Club Association and the European Leagues, revealing their plans to resume in July.
The Champions League group stage outfit now sit 15 points clear at the top of the Belgian first division with only one game to go before the 16-team league goes into a unique split.
According to the RFEF and the Danish Football Association, agreement has been reached for the women's Euro 2021, due to be hosted by England, to be played in 2022.
Ceferin says that playing remaining games behind closed doors would have to be an option across Europe. "Moreover, decisions by local authorities threaten to make a joint course of match days impossible".
The letter was sent hours after the Belgian league recommend to end the season with current standings.
"Both the KBVB and the Pro League are strong supporters of European football solidarity".
Referring to the working group set up by Uefa to consider how matches could be completed, the letter notes the idea of trying to finish national leagues first, then play the remaining Champions League and Europa League ties after that.
Officially, the Board of Directors of the Pro League on Thursday afternoon not even have been aware of the threat, unofficially, they knew that, with the European champions thought to be a threat of exclusion from participation in European competitions.
While that now looks ambitious, clearing the global fixtures from the same month does buy some more time as they aim to complete the Champions League and Europa League competitions as well as domestic leagues. The Belgian league announced earlier Thursday that Club Brugge would be awarded the title if the plan to end the season was confirmed at a general assembly meeting on April 15.
"The Board of Directors has unanimously decided that it is not desirable to continue the competition after June 30".
How will Champions League and Europa League be completed?
The question of how to deal with transfers, some of which have already been agreed upon for July 1 when the new season was meant to start, remains open.