"Although I do know someone who got a terrific solicitor and got everything even though the kids had left the home."
Every case is different - this makes it sound as if its only the solicitor ( rather than the circumstances) that makes the outcome more favourable.
Divorce is a big step and the OP's sister would be well advised to go and see a solicitor specialising in family law. She will be told that where money is no object that neither party will suffer unduly. Where money is an issue then the Court will take account of all assets available to both parties in reaching a decision as to how assets should be divided. A good rule of thumb is half of everything held jointly ( sort of unarguable) then take account of assets held in sole names, ability to earn, pension rights, etc.,etc.
Most non working wives are convinced that the husband has far more than he actually has. In reality, unless he is very clever and has gone to the trouble of hiding assets from everyone ( including Revenue), the Affidavit of Means and a quick trawl through Bank/Credit Card statements and tax returns will show all the assets. And if he has hidden assets, it is actually very hard to prove anything.
mf