Tigers director of rugby Richard Cockerill has nominated prop Ryan Bower, fly-half George Ford and flanker Pieter Myburgh as his additional players, while Leinster have added Aaron Dundon, Ian McKinley and experienced prop Stan Wright.
Clubs in the knock-out stages may nominate three additional players, one of which must be qualified to play in a front-row position.
Additional players registered in time for the Heineken Cup quarter-finals:
Biarritz Olympique: James Afoa (prop), Jean-Baptiste Roidot (lock)
Leicester Tigers: Ryan Bower (prop), George Ford (fly-half), Pieter Myburgh (flanker)
Leinster: Aaron Dundon (hooker), Ian McKinley (fly-half), Stan Wright (prop)
Northampton Saints: Ryan Glynn (scrum-half), Dan Vickerman (lock)
Perpignan: Gilles Arnaudies (back row), Thomas Dubois (prop), Romain Taofifenua (lock)
Toulon: Fabien Cibray (scrum-half), Pierrick Gunther (lock), Damien Tussac (prop)
Toulouse: Rupeni Caucaunibuca (wing), Jean-Bernard Pujol (wing)
Ulster: Conor Gaston (full-back/wing), Craig Gilroy (wing), Adam Macklin (prop)
