Sorry about your father's dementia. :(
As others' have said, it is smart to question what, if any, other opportunities there are with the portfolio. But, I think the smart thing to do is look at the actual #'s. What are the current rents, market rents, maintenance/capx costs and projections, what is the actual return on equity %, etc. That will give you a real barometer of the current situation.
But, the #'s are not the only consideration, at least shouldn't be in my experience. I have had properties starting with great returns, that I would've happily gotten rid-of at break-even a few years later, if I could. I would rather have quality properties, in good areas, that have good demand and general growth. Unfortunately, those typically don't have the highest # returns, but they do tend to have good appreciation over time and may have less "hassle factor."
And, as @Katie Balatbat mentioned the property taxes on those properties are likely far below current market values, which is helping the cashflow situation. As an example, if the sfr's were bought 10-15 years ago, it is likely they have at least doubled in value in that time. So, 2.9m assessments back then would double for any new purchases, including out of state. That is not a reason not to make changes, just something to put in the evaluation. In CA we do have a pretty advantageous property tax system, at least for the moment (LOL). Property taxes are 1% of assessed value + local abatements/voter indebtedness, etc. Usually that works out to be around 1.15-1.18%, or $34,220 (assuming 15yrs ago total assessment of $2,9m @ 1.18%). This would roughly equal to a trended assessment of $3.82m today or an estimated $45k annual property taxes currently. As an extreme example - if you exchanged all of the investment properties with the same assessment factors, that would equal around $68k in property taxes or almost an additional $2k per month!
That's not the only consideration, but it is something to think about. It is a lot harder to get into CA real estate these days, then even 10-15 yrs ago. And I have had an out of state rental property taxes increase 50% over a 1 year period!
I would also consult with a CPA, as Katie pointed out there are specific tax law changes coming up which would be good to know about.
I would also assess which properties you consider "good" rentals and if their are any "not-good" or "marginal" rentals. Maybe they are in good growth areas where rents and values seemed to increase greater than average, or maybe they consistently attract good tenants, etc. Then, you can consider possibly exchanging those that don't fit your goals.
In the current environment, I would be very cautious of making any sudden moves without fully assessing your current situation and returns. We are at very low affordability #'s which translates to higher values and with other stats, appears to suggest a relatively horizontal market with some dips for many years. That said, there are always opportunities somewhere and maybe multi-fam or other areas would be a good move. But, that requires analysis.
Also, there are many other investment opportunities with returns above what most real estate is offering now.
And, I think the assumption is that there are loans on ALL the properties? Are there any that are paid of and therefore a new loan on an exchange is moot?
And, and, since these properties are in CA, do any of the properties lend themselves toward adding an ADU and increasing the income potential. You may have easy opportunities to add income with some of the properties already owned.