Compared to an IRA, Solo 401k contribution limits are roughly ten times higher.There is no custodial requirement for the 401k.You don't need the additional expense and administration of an LLC to have checkbook control.There is a built in-Roth component whereas IRAs are either traditional or Roth, not both.A spouse can also participate in the same Solo 401k plan.The Solo 401k has additional tax benefits over an IRA when investing into real estate using leverage.You can borrow from a 401k, but not an IRABoth C-Corps and LLCs can adopt a Solo 401k.

As a self-administered qualified employer retirement plan, a Solo 401(k) requires access to quality guidance, and such custodial firms are simply not built to provide such guidance. 

@Rupert GrantGenerally if you're eligible for a Solo 401k, it makes sense compared to a self-directed IRA for many reasons: Compared to an IRA, Solo 401k contributions limits are roughly ten times higher.There is no custodial requirement for the 401k.You don't need the additional expense and administration of an LLC to have checkbook control.You can borrow up to $50k from the plan; IRAs do not allow participant loansThere is a built in-Roth component whereas IRAs are either traditional or Roth, not both.A spouse can also participate in the same Solo 401k plan.The Solo 401k has additional tax benefits over an IRA when investing into real estate using leverage.The penalties for prohibited transactions are less severe, though it's best not to utilize this benefit :)The one exception I can think of is if your primary goal is to self-directed Roth IRA funds.

If it is disability based on a disability that will end  (e.g. not ruled permanent) their income could end completely, yet they may have not job or income in the planning.Also ask about visiting grandkids, long term grandkids they have custody of. 

It was suggested that I take my RothIRA and put it in a custodial account and use it to purchase homes to flip? 

Every other weekend I'm actually not inside my house at all because I go out of town too spend time with my son, to whom the mother has custody of and I have visitation rights.

18 USC 1344 - Bank FraudWhoever knowingly executes, or attempts to execute, a scheme or artifice— (1)  to defraud a financial institution; or(2)  to obtain any of the moneys, funds, credits, assets, securities, or other property owned by, or under the custody or control of, a financial institution, by means of false or fraudulent pretenses, representations, or promises;shall be fined not more than $1,000,000 or imprisoned not more than 30 years, or both.

Has anyone dealt with a custodial account in the Seattle area?

She said she had a lot of problems at home (just won a custody battle) and couldn't afford to move out, otherwise she would have (same as the first tenants).

Long story short I went through some very difficult times in my early 20s due to a divorce and multiple custody battles.