If you set the MaximumErrorCount property on the Container to 3, that should do it. It defaults to 1 and so fails on the first error. You have three tasks inside, so a MaximumErrorCount of 3 should cause the Sequence Container to fail while 2 or less will allow it to succeed.
Also, if you're using Precedence Constraints to connect the tasks inside the Container and using the Constraint Evaluation option, be sure to change them to Completion.
You have to have the Sequence Container fail to utilize a Failure Precedence Constraint. But, as with the tasks inside the Sequence Container, this doesn't have to stop execution. The package also has a MaximumErrorCount property accessible from the Control Flow itself. You can set it to some number higher than the default (1) to have allow execution to continue after an error. Remember the part about using Completion Precedence Constraints earlier though.
As Julie Smith taught me, you set the MaximumErrorCount property to 0 to ignore all errors at the package level. this won't work for the Sequence Container because you want to trigger a Failure Precendence Constraint on the third error, and the only way to do that is to have the container fail on error #3.
Hope this helps,
Andy Leonard, Chief Data Engineer, Enterprise Data & Analytics