To'o had been earmarked to play on the right flank in his Blues debut outside Tom Trbojevic with Addo-Carr set to form a dangerous partnership with centre Latrell Mitchell on the other side.
To'o and Addo-Carr swapped roles as the Blues practised their attacking movements, including cross-field kicks at Homebush.
The pair insisted they would line up against the Maroons as initially expected at Townsville's QCB Stadium on Wednesday night.
"We were just going in and out just in case one of us gets injured; especially with my knee, obviously," To'o told NRL.com.
