I just went to a work shop at Michigan State University on poultry.
This is what they recommended.
Vaccinate for Mareck's only.
Feed medicated feed with this schedule
week 1: 100% medicated
week 2: 75% medicated and 25% unmedicated
week 3 50% medicated and 50% unmedicated
week 4: 25% medicated and 75% unmedicated
week 5 and beyond: 100% unmedicated
If you switch over from one exterme to the other the chicks have a hard time adjusting.
Hope this helps for future chicks.
Sorry about your loss. On a side note, I have never heard great things about mcm. Try to find a hatchery in your state or a neighboring state. Shorter time traveling and hopefully less stress too.
Sarah