Can you post some photos of your feed bag and the analysis tag?
I'm in Manitoba so I'm not sure how similar the process would be. Here in MB the vet lab that performs a full necropsy was run by the University of Manitoba. I did contact them directly to ask how to submit a deceased chicken, they directed me to go through my vet as they would need to submit a referral form. Here in MB for small flock owners (under 1000 birds) a necropsy falls under the avain influenza surveillance program and is covered by the government (I found this information on the government webpage for the vet lab, the veterinarian I go to was not aware of this coverage). They will submit all results not only AI results for the necropsy. I only had to pay the shipping fee from my vets office to the lab. Some labs allow in person drop off which could save this step. My vet charged me $60 for a 'case fee' and to dissect the tissues and send one of the chickens for necropsy that way instead of whole (I submitted two). Let me know if you have any other questions about the process, I know heartbreaking this must be for you, I have lost 5 in over a months time and have 4 that are stagnant in their recovery. It's tough!
