Not sure if this is the right place to post this question. Sorry if it's Not. 

Over the past several years my father has been buying out old mom and pop Lionel Train shops/repair shops. His health and life has been turned upside down with Non Hodgkin Lymphoma.  His collection of Lionel Trains currently has over to 4,500 pre and post war matching engine and tenders, over 7,000 box cars, cabooses, ect, and every conceivable repair part Lionel produced. He even has several copies of Lionel's factory repair manuals for many of the trains that I have never seen anywhere in my life.

How would you recommend going about selling such a huge collection? I get lost every time I look at this collect with what to do.

Thanks for any advice.