Do you mean that;
1. You have a childgallery list on some document that lists galleries under some specific document?
2. And you want this list to display the latest image from the galleries?
3. And when you click to go to some of the galleries, you want it to go to the last picture in picture view mode?
4. And next picture button should be disabled and previous show the second latest picture?
For 1 & 2, you should use [!MaxiGallery? &display="childgalleries" &order_by=`date` &order_direction=`DESC` &childgalleries_ids=`50`!]
For 3 & 4, create childgalleryTpl chunk like this:
<li>
<a href="[~[+maxigallery.pageinfo.id+]~]&pic=[+maxigallery.picture.id+]&from_id=[*id*]">
<img src="[(base_url)][+maxigallery.path_to_gal+]tn_[+maxigallery.picture.filename+]" class="thumbnail" title="[+maxigallery.strings.go_to_gallery+]" alt="[+maxigallery.strings.go_to_gallery+]" />
</a>
<p style="width:[+maxigallery.picture_width_thumb+]px; margin:0 auto;">[+maxigallery.pageinfo.pagetitle:htmlent+]</p>
</li>
And add it to the above call with &childgalleryTpl parameter.
Not sure that I got your question though..