If she was a landlord and hiring people to do work on the properties then you and she might want to put some assets into an irrevocable trust for the children.The above is made up but I think it will help drive the point home.For your parents to separate their rental property from other assets they own they need to not own the rentals.

Sample situation: A commercial property is worth $1,000,000 and is owned by an irrevocable trust.

While you are generally correct that permission can defeat an adverse-possession claim, there is also this concept called “easements” and “licenses” that can become irrevocable in certain situations.

Of course, the estate tax could still be a concern, BUT irrevocable trusts are a great tool for mitigating that risk... but I digress.If/when you get to that stage of your research (which might not be for a while), I'd suggest reaching out to a Qualified Intermediary here on BP (like @Dave Foster, for example) to make sure you get accurate info as it pertains to your specific situation.Whew, ok, that's enough from me.

A revocable trust would mean he could make changes, a Irrevocable trust would mean once trust is set up he can't make changes so depending on how much power he wants to retain I would start with a revocable trust,, if he were to die it would transfer and become a irrevocable trust. 

All contracts, options, or other devices not based upon a substantial consideration, or that are otherwise employed to permit an unlicensed person to sell, lease, or let real estate, the beneficial title to which has not, in good faith, passed to such party for a substantial consideration, are hereby declared void and ineffective in all cases, suits, or proceedings had or taken under this chapter; however, this section shall not apply to irrevocable gifts, to unconditional contracts to purchase, or to options based upon a substantial consideration actually paid and not subject to any agreements to return or right of return reserved.I regularly turn in these frauds.

No landscaping problems are irrevocable.

All contracts, options, or other devices not based upon a substantial consideration, or that are otherwise employed to permit an unlicensed person to sell, lease, or let real estate, the beneficial title to which has not, in good faith, passed to such party for a substantial consideration, are hereby declared void and ineffective in all cases, suits, or proceedings had or taken under this chapter; however, this section shall not apply to irrevocable gifts, to unconditional contracts to purchase, or to options based upon a substantial consideration actually paid and not subject to any agreements to return or right of return reserved.That appears to close the loophole. 

=============================Title Insurance Company is irrevocably committed to issue to buyer an owners title insurance policy covering the property with standard coverage customary in the state where property is located showing liability in the amount of the purchase price and showing insurable title to the property vested in buyer, subject only to the following(a) Title Insurance company standard exceptions(b) Liens for all current general and special real property taxes and assessments not yet due and payable(c) liens of supplemental taxes, if any assessed(d) any facts an accurate survey and/or a personal inspection of the property may disclose(e) the mortgage/deed of trust/deed to secure debt lien in connection with any buyer financing(f) any laws, regulations, ordinances (including but not limited to, zoning, building and environmental ) as to the use, occupancy, subdivision or improvement of the property adopted or imposed by any governmental body, or the effect of any non-compliance with or any violation thereof, including but not limited to, any disclosure an/or report required by ordinance(g) rights of existing tenants and/or occupants of the property (if any)(h) covenants, restrictions, easements and other matters that do not materially impair the value of the property or the use thereof(i) non-monetary encumbrances disclosed to buyer in writing prior to entering into this agreement (j) any other matter for which the title insurance company agrees to provide insurance at no additional cost to buyer===========================================================

Any buyer can walk in behind one of these frauds, make an honest offer, put down substantial consideration, and kick the unlicensed broker to the curb.From the statute:All contracts, options, or other devices not based upon a substantial consideration, or that are otherwise employed to permit an unlicensed person to sell, lease, or let real estate, the beneficial title to which has not, in good faith, passed to such party for a substantial consideration, are hereby declared void and ineffective in all cases, suits, or proceedings had or taken under this chapter; however, this section shall not apply to irrevocable gifts, to unconditional contracts to purchase, or to options based upon a substantial consideration actually paid and not subject to any agreements to return or right of return reserve