"Missing required value" error when the user try to submit a read-only sub form

the problem i am facing is as follow:-

1. i have approval1 & approval2 usernames
2. i have defined a deadline at user1 activity so that if he did not reply in 2 hours to escalated the task to approval2.
3. for each approval (approval1 and approval2) there are a required radio buttons named "Approval Decision" containing two values  either approve or reject.
4. Now the problem is that if approval1 did not response in two hours the tasks will be escalated to approval2 ,, then when approval2 select his decision from the radio and clicks complete button a "Missing required value" error will be raised on the radio button in the read-only sub form regarding approval1 selection (which in this case is null).
   

so how i can prevent the system from checking the required fields for a read-only form.

BR