Back Taxes

I currently live in South Carolina. I
owe back taxes in three states. The amount with interest and penalties is about $25,000. I also owe the IRS about the same from a few years ago.
My Mother is terminally ill and only has a month or so to live. I went to an accountant about 4 months ago. The person handling my case left the firm and the case sat until about two months ago. Another accountant took over my case and apologized for the dropping of the ball. They are just getting ready to send me my completed tax forms for the states and the IRS. They also are doing an Offer
to Settle. All that will be going to the various state and IRS agencies next week. If my Mother passes in January will the IRS hold up my inheritance. My Mother lives in Florida. Her attorney is the co-executor of the estate. I have three other sisters. My oldest sister is also co-executor of the estate. The estate is over $675,000. My youngest sister is also very ill and will need her share of the estate as quickly as possible. I am not in need of mine quickly but I don't want my tax problem to interfer with my younger sister getting her money. My Mother has converted all her assests to cash,
stocks, bonds and insurance policies.
She has told us all she wants everything split equally and divided as quickly as possible. My Mother also has no creditors to speak of.
My questions are 1) Will the IRS hold my sister's share of the money because of my back taxes? 2) Will the IRS stop the executor of the estate from releasing to me my proceeds of the estate? 3) How long might it take for the IRS to agree on an offer to settle? 4) What can I do if anything to speed up the process with the IRS?
5) Although I am not pleased with the accountants taking so long to inform me the accountant handling my case has left the firm I feel that now that all the back tax forms are being submitted this next week along with the Offer to Settle I am probably as well off atleast getting that done with the same firm. At this late date would I be slowing things up if I decided to change accountants? I am not asking if you think I should. I don't think that is fair to ask of you.
Thank you!

They won't take your sisters portion of the estate but if they find out about your sudden windfall, they may not agree to settle for anything less than full amount, including any interest penalties.