Comair does not currently have a flow-through agreement with Delta. Talks had been conducted in the past, however the proposal from Delta was apparently pretty one-sided, so the Comair pilot group rejected the proposal.
If I'm not mistaken, I believe the new DAL agreement has some sort of clause in it that prevents the new Delta mainline from awarding any new aircraft to a wholly-owned subsidiary without a flow-through--hence the reason Comair has been left out to dry in that department as of late. Maybe a Delta pilot or someone with knowledge of the agreement can correct me.
Comair"soon to be furloughed"FO