Let's make clear about your question.
(1)Does the device A, B and C are all BLE device? Or (2) device A and B are classic BT devices and device C is a BLE device?
In condition 1, the answer is no. EZ-Serial doesn't support multi-connection for BLE. If you want the function, you may refer to the following thread for some help. CYW20706 – BLE Secure Data Hub
In condition 2, the answer is yes. EZ-Serial can support BT and BLE connection at the same time. You can refer to the EZ- Serial user guide for the scan and connection for BT and BLE. https://www.cypress.com/file/455966/download
Sorry that I don't explain clearly. Yes, all BLE devices. And your spec is useful. I will check. Thank you very much.