How to implement quotation replies on Commerce orders by multiple users?
Use the Flag module to allow those users of a specific role to flag orders.

When configuring the (non-global) flag(s), attach appropriate fields to them, as described in Attaching fields to flags. These fields could perfectly match with the "multiple fields data to reply like price, qty, destination, etc." (as in your question).

If needed, use the Rules module to add all sorts of additional (custom) logic to the mix, eg:


only allow such flagging to happen within selected timeframes.
send (eMail) notifications to appropriate users.
perform field level validations (whatever may seem to be needed).
...