We're exploring creative ways to provide him with the cash needed for the down payment while avoiding triggering a taxable event.One strategy we're considering is purchasing his future primary residence ourselves, making the mortgage payments, and then, once we've built enough equity—comparable to the appraised value of his rental properties—transferring the title to him as a form of exchange.What are your thoughts on this approach?

Stay tuned and work with their folks for details, should be some exiting things in the future.  

I've consistently written about the forces of nature and her current and future effects on the real estate market (even while often being ridiculed and politicized on this very site for it) regardless: I personally moved and invested in coastal Oregon in 2018 from Venice Beach Los Angeles partly as a result of the trajectory of climate and have assisted several clients that specifically purchased on the Oregon Coast for their own 'climate havens,' investment and future retirement homes. 

Disallowed losses under wash sale rules increase the cost basis of replacement securities, potentially reducing future taxable gains.This post does not create a CPA-Client relationship.

Quote from @Raif Jochim: Bigger Pockets Community -I'm trying to plan for the future and have a question I'd like your thoughts on.  

However the most obvious benefit based on what you’re stating is that the depreciation from cost segregation will offset your $100k in taxable income from your commercial rental.There could be more benefits depending on future plans especially if you plan to sell any real estate in the near future. 

Let me walk you through some exciting trends that I’ve observed firsthand, which could shape the future of your portfolio.1.

We have offered to allow her to pay a reduced rent for the first few months as well but I am worried that may create some sort of limit on how much we can raise the rent on her in the future.

I'm currently building up capital for future ventures and properties that I find on market, as well as attempting to find the best brokerage where I can work under an individual who is already more established.

I have a wife and 3 kids and the weight of their futures on my back.