My father died in my sister's house July. She had PoA & as far as we know she was executor. but she won't let anyone see the will or see his things

All of my father's worldly possessions (which probably isn't too much) are in my sister's house because she moved him from Pennsylvania to her house in June after father's day. She will not tell any of us, his children, what is in the boxes in her house. She isn't unpacking them in front of us. She is not keeping any inventory or providing one to us. She has told us all that we are not welcome in her house. None of us has seen the will. We have not see any of his accounts. Insurance. The last time my older sister and I saw my dad he had alot of jewelry, coin collections, bonds, etc. All she ever tells us is that there is nothing. That he had nothing. That he gave everything away. Don't we have a legal right to go through his things too? to see his will? To have a say in what happens to his things? There are grandchildren too.