Unfortunately you can not link these separate schedules. You could close the existing business effective the beginning of 2017 and enter all of the expenses on the new commission related business schedule. You should clear out any UCC amounts simply by entering a disposition at the UCC and then transfer the UCC amount to the new commission business.
Some one else might also suggest just deleting the previous T2125 and re-enter all of this information in the new schedule as if the business was already existing. An acceptable explanation to CRA is that you were forced to change business type mid-stream due to the reporting obligations of this new income source. More of a paper shuffle then any thing but I understand this is an inconvenience to you.
