Wait and see if one of our legal experts joins in the discussion. I warn you that I am not one of them.
It does not look to me as if your sister, the executor, is required to transfer the house into a joint ownership by the eight of you; I thinks she is entitled to sell it and share out the proceeds. Like others in this thread, I think it is the wisest course of action.
I gather that your sister has not yet applied for a Grant of Probate. This might take a few months. She can not sell the house before she has the Grant. She can (presumably with some co-operation and assistance from other family members) get the house ready for sale. In the period between death and finalising the matter (either selling the house or putting it into your joint names) only she has any legal right to make decisions about how things are to be done. She can't do whatever she likes because all decisions must be made in the best interests of all the beneficiaries equally.
I think it would be wise of her to keep everybody in the loop by sharing information and listening to everybody's views. It would be good if everybody agreed on the best course of action. If that does not happen, she must make the decisions. That's what I meant when I said earlier that this is not a democracy.
It would be very risky to allow anybody to live in the house without a watertight legal agreement that involves payment of a proper rent and a commitment to co-operate with the sale of the house. That is very difficult to achieve.
Good luck with your family meeting.