It appears the Federal Law would require them to - "Simlarly Situated Individuals"
The group of covered employees, their spouses or dependent children who are covered under a group health plan maintained by the employer or employee organization. This group is receiving their benefits under the group plan and not through COBRA continuation coverage. They are most similarly situated to the circumstances of the qualified beneficiary immediately before the qualifying event.
View the original site for the links to work
http://www.dol.gov/elaws/ebsa/health/4.asp
For more info. visit www.SteveShorr.com
See also the employer group application - http://www.quotit.net/eproIFP/webpages/applications/applications_group.asp?license_no=0596610
check the employer contribution sections