CAN you? Yes. SHOULD you? No.
The ERM/EBC protocol is optimized for doing I/O and reporting errors.
ECOM100 Modbus/TCP are NOT optimized for I/O (e.g. see how long it takes to report a TCP connection error - 30 seconds?). You must write all the ladder logic and process all the mappings. If your ECOM100 is doing ANYTHING else (DirectSOFT programming port, HMI port, etc.), ALL of this must CO-EXIST on the same I/O network, and the bandwidth of the ECOM100 must do this other processing, in addition to the RX/WX instruction requests from your ladder logic to update I/O.
Save yourself a ton of issues - use the ERM/EBCs on an isolated I/O network. Use ECOM100 on a separate "data" network.