Last time I checked, rental income is reported by the taxpayer who is entitled to, and realizes, the income, and expenses are claimed by the one who is obligated for, and incurs, them. 

When two persons co-own rentals, aren't the income and expenses reported based on the economic substance, instead of being determined by who manage the rental activities?  

How do your clients intend to do "the transfer"?  How are they going to change the split (and thus the entitlement & obligation) of the income and expenses?  Are they going to change the ownership/title of the rentals?

Not to open another can of myself, but who are the father's heirs?  Is the son the only one?  They may also need to make clear their concept of property ownership for the purpose of the father's will or trust.  But then, I've just stepped into the turf of @IRonMaN  and @BobKamman who are, in this forum, the few almost-certified in bringing up new, tangential issues...

And I digress