If you have 2x WIDI devices, they will pair instantly to each other due to automatic pairing and role automation, they just plug and play. It will pair automatically with standard BLE MIDI controllers and similar. If you have 1x WIDI device you pair it manually with your operating system like iOS or MacOS.
Please take this rule of thumb for a better understanding. This means that if you have multiple BLE MIDI devices in your environment, this automatic pairing can lead to some confusion. Please note that WIDI devices pair automatically with other WIDI devices.
You can add up to 5x WIDI devices in one Bluetooth MIDI group with the improved app v1.2.XX (or higher) and firmware (v0098 and higher). You will need 2x WIDI device to connect two MIDI devices. You will need 1x WIDI device to pair with your Bluetooth MIDI equipped device like your MacOS, iOS, and standard Bluetooth MIDI controllers.