McMaster, like most universities is sort of a collection of different schools. The science, engineering, business, humanities faculties all have different administrations and different policies. While there are procedures for transferring between faculties they are not guarentted to remain static.
I highly suggest you call or email the administrative undergrad office in the degroote school of business asap:
http://ug.degroote.mcmaster. ca/contact/
Highlight your intentions and basically any information you can give.