Insurance policies are contracts; what  the insurer has to pay is governed by the terms of the contract. Generally, therefore, advances are only required if the policy says they are, and this applies typically only to your own insurance (e.g. if covered under your own no-fault).Her only recourse to try to move things along may be to sue the other driver--there is no law saying that someone has to wait until all costs and damages are finally known and paid for before suing (obviously, what is known will affect how much can be sued for). If she sues, her attorney may be able to work out, as part of a settlement, some immediate payment by the other driver's insurance. She therefore should consult with a personal injury attorney, many of whom will take cases like this on contingency (i.e. the attorney is only paid if and when the plaintiff is paid).