Question about intestate estate?

Alright, my father passed away and left an unsigned will. Everything was to go to me(executor and successor status) but he didn't get to sign it before he died. The three siblings will allow me to become executor like the will says, but they want their "say" in things(I'm assuming they want their share in the estate).
If it is indeed divided up equally(quartered) and we are each supposed to keep up on our part of the taxes and insurance and one inheritor does not pay it(say twice on the taxes and X number times on the insurance) can their share be foreclosed and distributed to the other siblings? If not, then what can be done?

The will is irrelevant. It's unsigned and won't be admitted.

YOu will be filing an intestate probate estate with yourself as the administrator. THe state law will degermine who gets what shares after all the bills and taxes have been paid. You can't forclose an interest in an estate. Ifyou are talking about a house and one party chooses not to pay his share, you'll end up in court. to get paid or force a partition suit and a sale of the house.

Unless it's a large estate, there won't be any taxes. Also, the estate may have to go through probate, which is a real mess. You need to talk to a good estate attorney.

The estate will be divided according to state law since he died intestate. If the four of you are the ONLY living heirs according to state law then you should each receive 1/4th of the net estate. However if your father had any siblings, they and their issue could be included in the list of heirs depending upon the state laws in effect at the time of his death.

Estate taxes, if any, will be paid from the estate's assets BEFORE the remainder, if any, can be divided.

There is no Federal inheritance tax. A few states still have inheritance taxes and those are the responsibility of the individual recipients if they were not paid by the estate on their behalf. If one of the beneficiaries fails to pay their tax, that will not affect the other beneficiaries.