It all sounds very interesting and very hopeful. If she did indeed keep her correspondence that could help authenticate some of the items and add weight to the authenticity of others. If at all possible, try and keep everything together until it has been fully assessed and researched. If some items have to go then try and get them copied, photographed and if applicable assessed before they are taken. try and ensure that records of disposal are kept in case you have any questions later on.

Good Luck
exmpa