Tax implications of taking under the radar loan

[Jeffrey Fecko]

I recently purchased an investment property with cash from my in-laws. The plan is to pay them back but I am worried they may not declare the interest income. I plan on having a frank conversation with them about it but want to fully understand the tax implications beforehand. If we are paying them back with "profit" the flows through to our personal account and they do now declare the interest income, does that create issues on my end?