Display related portfolio items in 7.1?

Hi,

I am building a demo site where I have three portfolios (for 3 different project categories).

When I open a portfolio's subpage, I need the other projects from the same portfolio to appear at the end of the page, as related projects.

I can ''manually'' add images with links to the other subpages but this doesn't seem very user friendly.

I understand correctly that this can happen through summary only with blogposts and events?  No way to work around this?

Thanks a lot

7.1 summaries don't support from gallery sections or portfolio pages. 

I don't know how far you are into your site build, however, there is one template where what you want takes place by default. It is the 7.0 Avenue. The index pages work just as you wish, images at the top, thumbnails underneath, that can be from a gallery page, that stacks images only when views from an index, or from a page with a gallery block, which can be slideshow, grid, wall (masonry). And being 7.0 you have the added bonus of pre designed landing/cover pages as well. 

Avenue is built to build walls and grids, using  index pages or summaries or both. They pull content from blogs, and gallery pages.  You can see the demo site here on this page, just down the page a bit:  https://www.squarespace.com/templates?onboarding_v7_1_0819=control

The reason I am so familiar with this template is I use it myself. For two sites. Here is my personal one with a lot of thumbnails and images :

my random views derrick Lee parker