Thanks for the info. It helps as to how to do the path. Imo, it'd be easier if there was a question in the selling of the investment property as to whether an exchange was completed. Exchanges take some time and when the timelines are assessed can around seven months and still fit within the legalities of an exchange. This means that it's quite likely that the sale & purchase would be in different tax years & may even fall outside of the filing deadlines so dealing with the exchange in the purchase of new property may or may not be the best area to have the link. All that said, it may ultimately be better in a more complicated situation like this to pay a tax pro.
