[sv-ac] Passing sequence as a formal arg to another sequence

lets take an example:
 
sequence S1 (lv_arg, a, b, c) ;
    a ##2 (b, lv_arg=din) ##2 c;
endsequence
 
sequence S2 (sequence Sarg (lv_arg, a, b, c) );
    Sarg (what do you use here)  or (rdy ##2 ack);
endsequence
 
sequence S4 ;
    integer lvar;
    S2 (S1(lvar, as, xack,  xdone));
endsequence
Two issues:
 
1) S1 is being passed a local variable that it assigns which flows out
of S1. Since local variables are declared inside sequences how do we
pass local variables into the sequence declaration for S2 which is using
sequence Sarg since we cannot pass any actual values until we
instantiate S2 in sequence S4
 
2) Does lv_arg flow out of Sarg into S2 and then into lvar in S4? 
 
-Faisal