i read it, you asked about using a wide band lambda on your dta,,, or hen use the one from your existing ecu aswell,,, both i doubt would be possible due to most aftermarket ecu's being quite basic with there closed loop control

vauxhall corsa B 1.2 8V uses a single wire lamda sensor, some use 3 wires, some use 4, not all of them give the same reading back to the ecu as it would read aswell

as chip mentioned as its generally a almost cude system then getting it mapped proper is the best alternative than rely on the ecu to correct the settings to make the perfect afr for the ecu, closed loop is great for what it does but most aftermarkets dont perform that well from what ive been told as most aftermarket ecu's are behind technology compared to current OEM ecu's fitted to cars

if you seen what denso and bosch are working on for the future as they have to work years in advance for the latest new car regs that come out every few years its then you discover just how basic ecu's in the aftermarket are and just how good the OEM stuff is and never really used to its fullest potential