BQ-1 and BQ-2 as well as the two amendments from the NDP are seeking to amend the same line. Even though there are no numbered lines in the schedule, there are still lines, so the same rule applies as in any clause in the bill. That's why if one amendment is adopted, the other ones can't be moved, because the schedule is going to be amended and it just wouldn't make sense to amend it again.
As I said, as in any other bill, once a line has been amended in a bill, it cannot be further amended. It can only be amended once. That's why if any one of the four amendments is adopted, the other ones cannot be moved.
(On clause 1)