Can I blend a bank loan, a vendor take-back, and my own cash without one lender objecting to the others?

In principle yes, and blending senior bank debt, a seller vendor take-back, and the buyer's own cash or equity is a normal, common way to fund a small business acquisition in Ontario. There is nothing about combining these sources that is prohibited or unusual as a matter of deal structure, and many acquisitions are financed exactly this way.

Practically, though, the bank providing the senior debt will usually want full visibility into, and often some say over, the terms of any vendor take-back sitting behind its own loan, including its size, repayment schedule, and whether it is subordinated to the bank's security, since all of that affects the bank's own risk assessment. The pieces of a blended financing structure generally need to be disclosed to and coordinated with each other, rather than assembled independently and presented to the bank as a finished plan, because a bank that objects to the seller-financing terms late in the process can force last-minute renegotiation with the seller, jeopardizing the closing timeline for everyone involved.