Hello @ao-on-wp,
Is it possible to set the primary category for a post? When on a single post I would like to determine from which category posts must be gotten from. Not the category with the lowest initial letter.
Posts in Sidebar has an option to choose the primary category just as WordPress does, i.e. the category with the lowest ID. The option is “Sort categories”:

For example, in this scenario of categories:
Category A where the ID assigned by WordPress is 300
Category B where the ID assigned by WordPress is 100
Category C where the ID assigned by WordPress is 200
Category Z where the ID assigned by WordPress is 50
if you activate that option, Posts in Sidebar will consider “Category Z” as the primary category.
Please, see if that can be enough for your needs.
Hi @ao-on-wp,
I just released the new Posts in Sidebar 4.15.0 that adds the new option as per your request.
You should receive the upgrade notification soon.
You will find the panel modified as follows:

Please, let me know.
WOW Aldo thanks very much for adding the feature to use the primary category as defined in the Yoast SEO Plugin. It makes it very easy to determine from which category posts must be pulled for posts that are published under multiple categories. I will give you more feedback in due course. Thanks again!