From what I can tell, if the TE is blocking the SS shifts to the WR on his side.
Bort has said that each of the LB's (I think it extends to all positions) has a progression he follows.
Here is how I believe it pans out in 43 defenses:
ROLB--FB-->HB
MLB--HB-->TE
LOLB--TE-->WR
SS--TE--WR
I can't swear that MLB and LOLB are correct. If you look at any 43 cover 2 man coverage with no blitzing where the FB stays to block and HB goes out for the pass, the R and M LB's both cover the HB.
In the 43cover1 you are almost assured that the SS and the LOLB will be covering the TE unless you blitz one or the other.
Bort replies to a concern I posted here about the issue of the the LB progressions here:
http://goallineblitz.com/game/forum_thread.pl?thread_id=1333730&page=13Hope that helps.