When my mom passed she had a living trust in it it gave each one of her children equal shares in said home. Two siblings live in the home and another one who was making the payments on the home for the rest of us defaulted and now it is going up for the highest bidder and I just found this out today honest truth. Is there a way I can stop the auction to give me a chance to get the money owed since I have equal shares. She can't do that can she

Some of the facts sound a little off. If the house is being auctioned for back taxes or a mortgage by a town or bank, not a sibling, you should have kept a better eye on the situation, and not just cheerfully allowed one sib to cover expenses for all of you. I highly doubt that a sibling could arrange an auction without official scrutiny of the deed, and certainly it couldn't finalize. You can try to rush over there and put a stop to it, but are you in a position to cough up what is owed? Laws about foreclosure sales vary by state, so you need to find what they are.

She got behind in the payments sorry I had been on deployment couldn't keep and eye on everything. Can I stop the auction.

Again, laws vary by state. Banks prefer to not have to foreclose, so would want you to pay them instead.
Some states even allow the owners to pay off what is due after the house has been sold to someone else! That is one reason they can sell for so little, and why banks don't like to foreclose. And foreclosures are postponed often, some over and over.
So... ask the bank handling it what the law is in that state, and while on the phone, ask how much is owed and can you get together.
Your sister has nothing to do with it.

Thanks so much for the help. Things are working out my sister an I are working together with bank.

Just to add, until the actual auction you should be able to negotiate with the bank to forestall the auction.

But I have to wonder how it got that far. If the sibling who was responsible for maintaining the mortgage couldn't do so on her own, why didn't that sibling contact the other siblings for help? Also, when a foreclosure is in process, notice is mailed to the address being foreclosed as well as the address of the person paying. So why didn't the siblings living in the house say something?

Finally, under federal law you can delay legal proceedings if you are active duty military. The bank must give you 90 days to get things in order.

... Also, when a foreclosure is in process, notice is mailed to the address being foreclosed as well as the address of the person paying. ...

Notice should be mailed to all owners of record, at their last known addresses.