Using Private Money with a Conventional Loan

[Donald Lisiecki]

Curious if anyone has found a way around this rule from the banks - Our bank will not allow us to use "gift money" for our 25% down payment on a conventional mortgage for an investment property.  However, my in-laws would like to invest in our business rather than letting their money sit in a low-interest account at a bank somewhere.  They want to give us the money we would need for our 25% down payment on an investment property and we would then pay them back over the course of the next few years.  However, the bank says we cannot use their money as our down payment.  Has anyone found a way to make this work?  It seems ridiculous that the bank can tell us we can't use OPM for a down payment.