To the acquisition of each property and the source of its down payment. The review needs purchase records, mortgage history, tax returns showing rental income and the sale closings, so that the net proceeds are shown to come from lawfully acquired assets.
Every property has its own chain
Lawful source of funds is not satisfied by showing a large deposit from a property sale. Each rental house is a separate chain: the purchase agreement and land-title transfer, the source of the down payment at that time, the mortgage and its servicing, the declared rental income over the years, and the sale documents with the mortgage discharge and net proceeds. For a house bought fifteen years ago, the down payment may have come from employment savings, and the engineer's T4s and tax returns for the years leading up to that purchase demonstrate it.
If a later house was bought using equity from the first, the refinancing documents link them. Land-title offices and lenders can usually reproduce old records, but requests take time. Tax returns from the Canada Revenue Agency's online account cover the income side.
Assemble all of this into a dated narrative before choosing a project, so that the gaps are found while there is still time to fill them.