Okay I'm going to I'm going to put on the my adjuster hat here. A couple of thinks that jump out is whether your state determines a driver is underinsured based on the at-fault driver's limits as they relate to damages or based on the at-fault driver's limits as compared to your limits. So in scenario one you would be entitled to $130k ($30k from at-fault insurance, $100k form UIM) and in the second scenario you would be entitled to $100k ($30k from at-fault insurance and $70k from UIM).
The attorney fees sounds really low and is not how a typical attorney contract reads in any of the states that I have handled claims. The usual agreement states that the attorney is owed 33% if the case is settled without litigation. If the case is litigated then the contract usually stipulates that the attorney is owed a higher percentage (I've seen 40% - 50%) of the recovery plus the costs/expenses incurred by the attorney is presenting the case. Some newer attorneys might have a lower contingent fee to attract business and some attorneys will lower their recovery if their client if they are actually going to make more money off the settlement than what the client does but I would be extra wary of the attorneys with low contingency fees.
The biggest issue here is whether any of the parties that have any assets. I would try and find an attorney and pay they to do a Lexis Nexis search on any property they own. If they don't have much then I wouldn't even bother trying to recover from them, just take the insurance money and cut your losses. I would take a shot at getting the health insurance lien reduced by talking to the subrogation adjuster to see about a slight decrease in the bill. So here are how the two scenarios could play out with me knowing nothing about the specific injuries.
Scenario 1 (Settlement)
Take Insurance Money: $130,000
Take to Health Ins get $10k reduction: ($85k)
Less Wages/Self-Pay Bills: ($12k)
Net: $33,000
Scenario 2 (Trial)
Verdict: $400,000
Attorney Fees: ($160,000) [I am assuming 40% which is typical for a case that goes to verdict]
Health Insurance Lien: ($95,000) [They usually don't want to negotiate after a verdict as they have statutory rights]
Your Out of Pocket Expenses: ($12,000)
Depositions: ($5,000) [If you want to prove a sham transfer then you're going to have to depose them all]
Medical Expert: ($7,500) [You have to have medical expert speak about the nature of the injuries]
Assume 1 more expert: ($7,500)
Court Costs: ($2,500)
Maybe hire PI: ($2,000) [Again you have to prove sham transfer]
Net: $108,500
Okay so two or three years down the road the case has been finally reached a verdict and you are better off by $75,500 than you were before the accident right? Maybe. The verdict will be converted to a judgment and then the Defendants will likely say sorry we don't have the money. The court doesn't really help in collection so you will have to do two things. First the Defendants are sometimes deposed about what assets they have to determine if there is any recovery potential. You could file a garnishment action and have money directed from their bank accounts/job to you until the judgment is satisfied. The problem with that is you have to file the garnishment every time they change jobs or a bank.
I've obvious made some assumptions here but on its face it appears that the insurance money is enough to pay back your out-of-pocket expenses but not much else. While that sucks at least the accident shouldn't cost you anything financially. Whatever you choose the best of luck to you.