You pretty much need an estate lawyer just to navigate all of the legal stuff associated with a person's passing, and I went through this a few years ago with my own father.
But the majority of attorneys who handle estates can also handle all of the financial and personal details as well. The only times this really NEEDS to get complicated is when the estate has a negative net worth (which means a potential lack of funds to close the estate), contains businesses that need to be sold or split up, or when survivors fight each other for their percentage of the inheritance.
I mentioned to Schwab that she had passed and they froze the account until I could prove the estate was less than $14 Million. Needless to say this was a disaster as I was in a foreign country writing checks left and right.
The issue was that it was foreign addressed account of a US domiciled bank. The IRS places the liability of the taxes on the bank if the estate is over $12 Million. Schwab would recognise a letter from the IRS stating that or any US probate court. My Mom's estate with no US assets has no US based probate court access. The IRS rule was enacted after our joint-account was opened and blew up our estate plan.
Needless to say in 30 years I only had one problem with Schwab (which I had praised as the best bank ever until that moment). I have been unwinding all of my families Schwab accounts.
I've been thinking about building a platform to help prepare for and guide families who are faced with this kind of situation.