Can a child avoid estate and inheritance taxes in the state of New Jersey by becoming a co-owner of a house while the parent is still alive?

My mother has a house in Bergen County, NJ. She is currently the sole owner as our father passed away several years before. The house currently has no mortgage on it and was bought in the early 1980''s for about $95k. Improvements documenting about $200k have been done to the house and the current estimated market value I''d say is in the $450k to $500k range. My mother has 2 children. If one of us were to become a coowner on the house by adding our name to the deed, what happens to the estate when she passes away? Do we get sole ownership and do we have to pay estate/inheritance taxes? After she passes, can we then add the other child to the deed so thst now both children own the house? Note, that this is my mother''s primary residence but for either of her children, it would be a second home and not their primary residence.