Can an extension kit be added to the Wireless starter kit?

Having recently purchased a v3+ wireless starter kit to attach to my Vaillant boiler, I’ve discovered that this kit does not allow ebus and that the extension kit is required.

If I purchase an extension kit, can this be installed in place of the wireless receiver from the kit? or will I need to return the wireless kit and buy wired+extension. (Which annoyingly almost doubles the cost of the base installation as the wired kits are never on offer)