I have a batch of week old bantams now, growing fast, and was planning on getting a standard chick in the next few days so I could put them all together and they'd still be roughly the same size. I would have preferred getting them all from the same source and at the same age, but none of the local places have everything I wanted at the same time. Local feed store said that I shouldn't mix chicks from different places as they would give each other diseases. How great a risk is this? Otherwise, I have to commit to one store and date per chick raising season? This seems a bit restrictive. All local chicks are vaccinated for Marek's. In addition, if I can't mix them, I'd have to get at least three chicks and a separate brooder set-up to provide each other company, which is more than I intended. On the other hand, I'd hate for chicks die from cross-contamination. On the other other hand, I suspect that many of the chick batches at different local stores come from the same hatcheries. Any personal experience with this?