You might want to try this in the Access Database.
a) Link the excel file in Access
b) Create an update query to update the excel file's "mgr mgr ID".
c) Pull original table A and excel file in the query
d) Link table A's "mgr.ID" with excel file's "employee ID"
e) Update excel A's "mgr.mgr. ID" with table A's "mgr. ID" if the link in (d) is not null.