Hi Nessma,
If I understand you correctly, you want to setup some business rules so that if an administrator and/or manager accept or reject a request, you accordingly decide if the overall status is accepted or rejected.
The first step is to actually define the business rule. So if:
1) Both accepted = acceptance
2) Both rejected = rejection
3) Admin accepted + Manager rejected =?
4) Manager accepted + Admin rejected = ?
Once you decide the logic, you can then apply it in a workflow (if your data model allows). So if the approval is a custom entity, every time a new record is created, you update a parent entity so you set the overall value to accept or reject accordingly.
This might work if your data model and entities relationships allow. If not, you might need to write a custom plugin to apply these business rules.
Hope this helps! Please click on "yes" if you found this response helpful.