Form to Be Approved by Many

I have already created a Form, but the issue here is that the form has to be sent to many people for Approval. Each Approver has a specific clearance Section of the Form. the Query here is that they need to fill their sections with the required comments and email the form back to the sender. the sender has to then send the form to the next Approver. is there a way that if the approver fills certain fields they get Auto readonly while the other fields that are not filled remain fillable.

Note All the Approvers have only Adobe reader so cannot use Create and Distribute.

Whats the best way in acrbat because if I use buttons any one can click the button and it get readonly is there a better way