Google Maps plugin for Travel Blog

Hi there.
First of all: I tested a lot of google maps plugins for wordpress but haven’t found my ideal solution yet.
Here is what I’m looking for:
My sister is going on a world trip starting in 2 weeks and I’m currently in the process of developing a blog for her. I want to offer her the opportunity to add a little map snippet under each blog post with her current location. This is currently possible with a lot of plugins. So far, so good.
The next step: Idealwise I would love to have the following functionality: Every marker which is set within the map of an individual blog post will be automatically copied to a large overview map. All these individual markers will be then connected with each other so that the visitor can see which places my sister already have visited. Additionally each marker which is copied to the overview map is linked to the blog post which the marker belongs to. This overview map is located under the trip overview section of the blog.

Has anyone of you seen anything similar to this?
Or has anyone an idea how I could realize something similar to what I wrote above?

Thanks a lot
jan