Can I have a document signed in a specific order?

Yes. When preparing the envelope, turn on signing order: you number the signers (1, 2, 3…). The document goes to signer #1 first; once they've signed, the next one is automatically notified, and so on. Until the previous signer has signed, the following ones receive nothing.

If order doesn't matter, keep the parallel mode: everyone receives the document at the same time. You can also add recipients in carbon-copy only, with no field to sign.