I want to implement functionality like. When any user create
issue, he should assign only to group MFG(not other than
MFG), then MFG group will try to resolve at there end, if
they resolve issue then MFG group will update status to
close, and if not then MFG group user will forward(assign)
to SUPPER group, and supper group will assign to expert person.

What I did As follows.

1)created two Issue tracking list one is "ABC" another is "PQR"
2) Also applied permission on ABC and PQR list. because end
user should not interact directly with consultant, one group
of 4 person is present between end users and consultant,
this group is mediator.
3) copy workflow is created. it will copy list of items from
ABC list to "PQR" List. Here Im facing problem that workflow
will not copy item because user of "ABC" does not have
access to "PQR". if i give contribute permission on both
list then workflow work correctly. I want that User of List
ABC should not see the PQR list and workflow copy item from
one list to other list.

Can any one help me?
thanx in advance