Celtic and Chelsea have applied to join the increasingly powerful G14 group of European clubs, with a view to ensuring that players who break contracts do not prosper.
The G14 lobbying group already include Manchester United and Liverpool, as well as the likes of AC Milan, Real Madrid, Juventus and Barcelona.
However, they are looking to extend their influence by expanding, with Rangers, Lazio, Roma, Parma and Hertha Berlin already having shown an interest in joining.
Now Chelsea, Celtic and Sporting Lisbon have also applied to be considered as members, with a decision set to be taken next month.
The G14 group, which was formed four years ago, were widely consulted during the proposed breakaway Super League negotiations and have recently established a formal presence by opening offices in Brussels.
Thomas Kurth, general manager of the G14, told football business newsletter Soccer Investor: "After the first five applied, three more clubs have come forward. They are Sporting Lisbon, Chelsea and Celtic."
There is not understood, at least yet, to have been any application from Arsenal, Leeds or any other British club.
The existing G14 group are Manchester United, Liverpool, Real Madrid, Barcelona, Juventus, AC Milan, Inter Milan, Bayern Munich, Borussia Dortmund, Marseille, Paris St Germain, Ajax, PSV Eindhoven and FC Porto.
PA