For the EL the u21 players must have been with the club for an uninterupted period of 2 years (can have been at the club for that, then out on loan, then returned and be eligible). So Lamela (if signed), Eriksen (if signed) and Fryers won't be eligible for the B-list and must thus be registered as part of the 25 man A-list squad if they are to take part.
In addition to that the EL has the additional "club trained player" regulations. 4 of the 8 home grown players must have been trained at the club.
Regulations:
http://www.uefa.com/MultimediaFiles.../Regulations/01/62/69/60/1626960_DOWNLOAD.pdf (pdf)
I'm not entirely confident about this, but I think if a player goes out on loan that period doesn't count towards them being trained at the club. Would be great if someone can either correct me or say that I'm right here.
I'm quite sure Lennon and Townsend both qualify. Not sure about Rose. I don't think we have any others that qualify, but once against I could be wrong.
I think we might have to leave someone out of the EL squad, but I suppose we'll know soon enough.